Transaction log acceleration

ABSTRACT

Apparatuses, systems, methods, and computer program products are disclosed for transaction log acceleration. A log module is configured to determine transaction log records indicating a sequence of operations performed on data. A commit module is configured to send transaction log records to one or more volatile memory pages accessible over a network. Volatile memory pages are configured to ensure persistence of transaction log records. A storage module is configured to send transaction log records to a non-volatile storage device in response to an acknowledgment that one or more volatile memory pages store the transaction log records.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a divisional of U.S. patent application Ser. No.14/732,675 entitled “TRANSACTION LOG ACCELERATION” and filed on Jun. 6,2015, for Dhananjoy Das which claims the benefit of U.S. ProvisionalPatent Application No. 62/164,364 entitled “TRANSACTION LOGACCELERATION” and filed on May 20, 2015, for Dhananjoy Das, both ofwhich are incorporated herein by reference.

TECHNICAL FIELD

This disclosure relates to transaction logs and more particularly toaccelerating storage of transaction log entries using network attachedhardware.

BACKGROUND

Transaction logs and other data structures are often used byapplications, such as database systems, to organize and track data asthe applications execute. Once an application sends an entry of atransaction log or other data structure to be stored, the applicationmay wait for an acknowledgment before executing or processing the nexttransaction or event. Therefore, the speed with which an entry of atransaction log or other data structure is stored may directly affectthe performance of the associated application, such as a database systemor the like.

Additionally, if power is interrupted or another error is encounteredwhile an entry of a transaction log or other data structure is beingstored (e.g., while an entry is “in flight”), the entry and associateddata may be lost. If an entry and associated data is lost, due to apower failure, an improper shutdown, or other error, the execution stateof an associated application may also be lost, with one or more recentchanges, transactions, or the like.

SUMMARY

Apparatuses for transaction log acceleration are presented. In oneembodiment, a non-volatile storage device comprises a non-volatilestorage medium and is in communication with a storage client over anetwork. A volatile memory buffer of a non-volatile storage device, incertain embodiments, is configured to receive transaction log entries ofa storage client over a network. A volatile memory buffer, in a furtherembodiment, is configured to store transaction log entries in anon-volatile storage medium in response to a trigger. A volatile memorybuffer, in one embodiment, is configured to retrieve one or moretransaction log entries from a non-volatile storage medium in responseto receiving an identifier from a storage client after a trigger. One ormore retrieved transaction log entries, in certain embodiments, are sentfrom a storage client to a second non-volatile storage device over anetwork.

Other apparatuses for transaction log acceleration are presented. In oneembodiment, a log module is configured to determine database log recordsindicating a sequence of operations performed on data of a databasesystem. A commit module, in certain embodiments, is configured to senddatabase log records to one or more volatile memory pages accessibleover a network. Volatile memory pages, in one embodiment, are configuredto ensure persistence of database log records. A storage module, in afurther embodiment, is configured to send database log records to anon-volatile storage device in response to an acknowledgment that one ormore volatile memory pages store the database log records.

Additional apparatuses for transaction log acceleration are presented.In one embodiment, an apparatus includes means for storing journaltransactions in volatile memory of a storage device. An apparatus, in afurther embodiment, includes means for storing journal transactions in asecond storage device in response to confirming storage of the journaltransactions in volatile memory of a storage device. A second storagedevice, in certain embodiments, has a higher latency than volatilememory of a storage device.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the advantages of this disclosure will be readilyunderstood, a more particular description of the disclosure brieflydescribed above will be rendered by reference to specific embodimentsthat are illustrated in the appended drawings. Understanding that thesedrawings depict only typical embodiments of the disclosure and are nottherefore to be considered to be limiting of its scope, the disclosurewill be described and explained with additional specificity and detailthrough the use of the accompanying drawings, in which:

FIG. 1 is a schematic block diagram illustrating one embodiment of asystem for transaction log acceleration;

FIG. 2 is a block diagram illustrating another embodiment of a systemfor transaction log acceleration;

FIG. 3 is a block diagram illustrating a further embodiment of a systemfor transaction log acceleration;

FIG. 4 is a block diagram illustrating an additional embodiment of asystem for transaction log acceleration;

FIG. 5A is a schematic block diagram illustrating one embodiment of anacceleration module;

FIG. 5B is a schematic block diagram illustrating another embodiment ofan acceleration module;

FIG. 6 is a schematic flow chart diagram illustrating one embodiment ofa method for transaction log acceleration;

FIG. 7 is a schematic flow chart diagram illustrating a furtherembodiment of a method for transaction log acceleration; and

FIG. 8 is a schematic flow chart diagram illustrating another embodimentof a method for transaction log acceleration.

DETAILED DESCRIPTION

Aspects of the present disclosure may be embodied as an apparatus,system, method, or computer program product. Accordingly, aspects of thepresent disclosure may take the form of an entirely hardware embodiment,an entirely software embodiment (including firmware, resident software,micro-code, or the like) or an embodiment combining software andhardware aspects that may all generally be referred to herein as a“circuit,” “module,” “apparatus,” or “system.” Furthermore, aspects ofthe present disclosure may take the form of a computer program productembodied in one or more non-transitory computer readable storage mediastoring computer readable and/or executable program code.

Many of the functional units described in this specification have beenlabeled as modules, in order to more particularly emphasize theirimplementation independence. For example, a module may be implemented asa hardware circuit comprising custom VLSI circuits or gate arrays,off-the-shelf semiconductors such as logic chips, transistors, or otherdiscrete components. A module may also be implemented in programmablehardware devices such as field programmable gate arrays, programmablearray logic, programmable logic devices, or the like.

Modules may also be implemented at least partially in software forexecution by various types of processors. An identified module ofexecutable code may, for instance, comprise one or more physical orlogical blocks of computer instructions which may, for instance, beorganized as an object, procedure, or function. Nevertheless, theexecutables of an identified module need not be physically locatedtogether, but may comprise disparate instructions stored in differentlocations which, when joined logically together, comprise the module andachieve the stated purpose for the module.

Indeed, a module of executable code may include a single instruction, ormany instructions, and may even be distributed over several differentcode segments, among different programs, across several memory devices,or the like. Where a module or portions of a module are implemented insoftware, the software portions may be stored on one or more computerreadable and/or executable storage media. Any combination of one or morecomputer readable storage media may be utilized. A computer readablestorage medium may include, for example, but not limited to, anelectronic, magnetic, optical, electromagnetic, infrared, orsemiconductor system, apparatus, or device, or any suitable combinationof the foregoing, but would not include propagating signals. In thecontext of this document, a computer readable and/or executable storagemedium may be any tangible and/or non-transitory medium that may containor store a program for use by or in connection with an instructionexecution system, apparatus, processor, or device.

Computer program code for carrying out operations for aspects of thepresent disclosure may be written in any combination of one or moreprogramming languages, including an object oriented programming languagesuch as Python, Java, Smalltalk, C++, C#, Objective C, or the like,conventional procedural programming languages, such as the “C”programming language, scripting programming languages, and/or othersimilar programming languages. The program code may execute partly orentirely on one or more of a user's computer and/or on a remote computeror server over a data network or the like.

A component, as used herein, comprises a tangible, physical,non-transitory device. For example, a component may be implemented as ahardware logic circuit comprising custom VLSI circuits, gate arrays, orother integrated circuits; off-the-shelf semiconductors such as logicchips, transistors, or other discrete devices; and/or other mechanicalor electrical devices. A component may also be implemented inprogrammable hardware devices such as field programmable gate arrays,programmable array logic, programmable logic devices, or the like. Acomponent may comprise one or more silicon integrated circuit devices(e.g., chips, die, die planes, packages) or other discrete electricaldevices, in electrical communication with one or more other componentsthrough electrical lines of a printed circuit board (PCB) or the like.Each of the modules described herein, in certain embodiments, mayalternatively be embodied by or implemented as a component.

Reference throughout this specification to “one embodiment,” “anembodiment,” or similar language means that a particular feature,structure, or characteristic described in connection with the embodimentis included in at least one embodiment of the present disclosure. Thus,appearances of the phrases “in one embodiment,” “in an embodiment,” andsimilar language throughout this specification may, but do notnecessarily, all refer to the same embodiment, but mean “one or more butnot all embodiments” unless expressly specified otherwise. The terms“including,” “comprising,” “having,” and variations thereof mean“including but not limited to” unless expressly specified otherwise. Anenumerated listing of items does not imply that any or all of the itemsare mutually exclusive and/or mutually inclusive, unless expresslyspecified otherwise. The terms “a,” “an,” and “the” also refer to “oneor more” unless expressly specified otherwise.

Aspects of the present disclosure are described below with reference toschematic flowchart diagrams and/or schematic block diagrams of methods,apparatuses, systems, and computer program products according toembodiments of the disclosure. It will be understood that each block ofthe schematic flowchart diagrams and/or schematic block diagrams, andcombinations of blocks in the schematic flowchart diagrams and/orschematic block diagrams, can be implemented by computer programinstructions. These computer program instructions may be provided to aprocessor of a computer or other programmable data processing apparatusto produce a machine, such that the instructions, which execute via theprocessor or other programmable data processing apparatus, create meansfor implementing the functions and/or acts specified in the schematicflowchart diagrams and/or schematic block diagrams block or blocks.

It should also be noted that, in some alternative implementations, thefunctions noted in the block may occur out of the order noted in thefigures. For example, two blocks shown in succession may, in fact, beexecuted substantially concurrently, or the blocks may sometimes beexecuted in the reverse order, depending upon the functionalityinvolved. Other steps and methods may be conceived that are equivalentin function, logic, or effect to one or more blocks, or portionsthereof, of the illustrated figures. Although various arrow types andline types may be employed in the flowchart and/or block diagrams, theyare understood not to limit the scope of the corresponding embodiments.For instance, an arrow may indicate a waiting or monitoring period ofunspecified duration between enumerated steps of the depictedembodiment.

In the following detailed description, reference is made to theaccompanying drawings, which form a part thereof. The foregoing summaryis illustrative only and is not intended to be in any way limiting. Inaddition to the illustrative aspects, embodiments, and featuresdescribed above, further aspects, embodiments, and features will becomeapparent by reference to the drawings and the following detaileddescription. The description of elements in each figure may refer toelements of proceeding figures. Like numbers may refer to like elementsin the figures, including alternate embodiments of like elements.

FIG. 1 depicts one embodiment of a system 100 for transaction logacceleration. The system 100, in the depicted embodiment, comprises oneor more acceleration modules 150. At least a portion of an accelerationmodule 150 may be part of and/or in communication with one or more of anon-volatile memory controller (e.g., a non-volatile memory mediacontroller 104, a device driver or storage management layer (SML) 130),or the like. The acceleration module 150 may operate on a non-volatilememory system of a computing device 110, which may comprise a processor111, volatile memory 112, a communication interface 113, or the like.The processor 111 may comprise one or more central processing units, oneor more general-purpose processors, one or more application-specificprocessors, one or more virtual processors (e.g., the computing device110 may be a virtual machine operating within a host), one or moreembedded processors or microprocessors, one or more processor cores, orthe like. The one or more communication interfaces 113 may comprise oneor more network interfaces configured to communicatively couple thecomputing device 110 and/or the non-volatile memory controller 104, 130to a communication network 115. The communications network 115, as usedherein, comprises one or more logical or physical channels fortransmitting and/or receiving data. The communications network 115 maycomprise an Internet Protocol network, a Storage Area Network, a storagefabric, a local area network (LAN), a wide area network (WAN), a wirednetwork, a wireless network, or the like.

The computing device 110 may further comprise a non-transitory, computerreadable storage medium 114. The computer readable storage medium 114may comprise executable instructions configured to cause the computingdevice 110 (e.g., processor 111) to perform steps of one or more of themethods disclosed herein. Alternatively, or in addition, theacceleration module 150 may be embodied, at least in part, as one ormore computer readable instructions stored on the non-transitory storagemedium 114. As described in greater detail below, in certainembodiments, the computing device 110 comprises little or nonon-volatile storage, using one or more non-volatile storage devices102, 121 over the communication network 115 for non-volatile storage.

The non-volatile memory system 100, in the depicted embodiment, includesone or more acceleration modules 150. The acceleration module 150, inone embodiment, is configured to manage storage of transaction logentries for one or more storage clients 116 (e.g., a database systemstorage client 116 a). The acceleration module 150, in certainembodiments, stores one or more transaction log entries in a volatilememory 1013 of a non-volatile storage device 102 over a network 115. Thevolatile memory 1013 of the non-volatile storage device 102 may beconfigured to automatically preserve the data it stores in anon-volatile storage medium 122 of the non-volatile storage device 102in response to a trigger, such as a power failure, an improper shutdown,a power level failing to satisfy a threshold, or the like, therebyensuring that the data is preserved and non-volatile, even though thevolatile memory 1013 is volatile (e.g., with associated logic, such asthe ACM 1011 described below). The volatile memory 1013 of thenon-volatile storage device 102 may have a lower latency than the secondnon-volatile storage device 121, than the local computer readablestorage medium 114 (e.g., a local non-volatile storage device) of thehost computing device 110, or the like, even over the network 115. Forexample, in certain embodiments, the host computing device 110 and/orthe storage client 116 may use a high performance interconnect and/orprotocol such as direct memory access (DMA), 3^(rd) party DMA, remoteDMA (RDMA), Infiniband, Fibre Channel, or the like over the network 115,to minimize latency.

A storage client 116, as used herein, may comprise software (e.g.,computer executable code stored in a computer readable storage medium)and/or logic hardware configured to send, receive, or otherwise use datafrom a non-volatile storage device 102, 121. A storage client 116 mayinclude a local storage client 116 operating on the computing device110, a remote storage clients 116 accessible over the network 115 and/ornetwork interface 113, or the like. The one or more storage clients 116may include one or more operating systems, file systems, databasesystems 116 a, server applications, kernel-level processes, user-levelprocesses, applications, computing devices 110, or the like.

A database system 116 a, as used herein, may comprise software (e.g.,computer executable code stored in a computer readable storage medium)and/or logic hardware configured to store and/or provide organizedaccess to data. A database system 116 a may allow other clients 116 orusers 116 to define, create, query, update, and/or administer databases,tables, or other collections of data, using a query language, agraphical user interface (GUI), a command line interface (CLI), or thelike. A database system 116 a may organize data according to one or moremodels, such as a relational model, a hierarchical model, an objectmodel, a document model, an entity-relationship model, anentity-attribute-value model, and/or another model. As described above,a database system 116 a may record certain transactions in a databaselog or other transaction log data structure. Recording transactions intransaction log may allow a storage client 116 such as a database client116 a to undo and/or redo one or more transactions, to recreate data(e.g., one or more volatile data structures lost due to a restart eventof other trigger), as a backup or redundant copy of data, to replay andapply transactions on a copy of data in another location, or the like.

Once a storage client 116 sends an entry of a transaction log or otherdata structure to be stored, the storage client 116 may wait for anacknowledgment before executing or processing the next transaction orevent. The speed (e.g., latency) with which an entry of a transactionlog or other data structure is stored may directly affect theperformance of the associated storage client 116, such as a databasesystem 116 a, or the like.

The volatile memory 1013, as used herein, may comprise a memory mediumand/or storage medium that uses electrical power (e.g., from the primarypower connection 136, from the secondary power supply 124, or the like)to maintain stored data. A volatile memory 1013 may include randomaccess memory (RAM) such as dynamic RAM (DRAM), static RAM (SRAM),embedded block memory (BRAM), or the like. The volatile memory 1013 maycomprise, and/or be segmented, divided, or allocated as one or morepages, buffers, elements, modules, or devices. In response to thevolatile memory 1013 storing data, such as a transaction log entry, froma storage client 116, the acceleration module 150 may store the data inthe second non-volatile storage device 121 (e.g., an intendeddestination for the data). By first storing data, such as database logentries or other transaction log entries, in the volatile memory 1013,which may have a lower latency, in certain embodiments, the accelerationmodule 150 may accelerate operation of the associated storage client 116without sacrificing data integrity, allowing the storage client 116 tocontinue with the next transaction or entry before the previoustransaction or entry is stored in the second non-volatile storage device121, which may have a higher latency than the volatile memory 1013.

By separating the non-volatile storage device 102, with includedvolatile memory 1013, from the host computing device 110 and placing thenon-volatile storage device 102 on the communications network 115, inone embodiment, storage clients 116 from multiple locations (e.g.,multiple computing devices 110) on the communications network 115, maystore data such as transaction log entries in the non-volatile storagedevice 102. In this manner, in certain embodiments, multiple storageclients 116 and/or computing devices 110 may take advantage of the lowlatency and/or ensured persistence of the volatile memory 1013. One ormore host computing devices 110 storing data in the non-volatile storagedevice 102, may have little or no local non-volatile storage (e.g., maybe “diskless”). Storing data such as transaction log entries (e.g.,database log entries) in one or more non-volatile storage devices 102,121, instead of or in addition to storing the data in local storage ofthe host computing device 110 executing the associated storage client116 (e.g., database system 116 a), in one embodiment, may facilitatefaster recovery if the host computing device 110 or a component thereoffails, as the data may be immediately or quickly available to anotherhost computing device 110 over the network 115.

In one embodiment, the acceleration module 150 may comprise executablesoftware code, such as a device driver, SML 130, or the like, stored onthe computer readable storage medium 114 for execution on the processor111. In another embodiment the acceleration module 150 may compriselogic hardware of one or more non-volatile storage devices 102, such asa non-volatile storage medium controller 104, a device controller, afield-programmable gate array (FPGA) or other programmable logic,firmware for an FPGA or other programmable logic, microcode forexecution on a microcontroller, an application-specific integratedcircuit (ASIC), or the like. In a further embodiment, the accelerationmodule 150 may include a combination of both executable software codeand logic hardware (e.g., a controller comprising a device driver suchas an SML 130 executing on a host computing device 110 and a hardwarecontroller 104 disposed on the non-volatile storage device 102).

In one embodiment, the acceleration module 150 is configured to providestorage requests to the SML 130, to receive storage requests from theSML 130 via the network 115, or the like. The acceleration module 150may be further configured to transfer data to/from the SML 130 and/orstorage clients 116 via the network 115. Accordingly, the accelerationmodule 150, in some embodiments, may comprise and/or be in communicationwith one or more direct memory access (DMA) modules, remote DMA modules,bus controllers, bridges, buffers, and so on to facilitate the transferof storage requests and associated data. In another embodiment, theacceleration module 150 may receive storage requests as an API call froma storage client 116, as an IO-CTL command, or the like. Theacceleration module 150 is described in greater detail below with regardto FIGS. 5A and 5B.

According to various embodiments, a non-volatile storage controller(e.g., a device driver or SML 130 and/or a non-volatile storage mediumcontroller 104) comprising the acceleration module 150 may manage one ormore non-volatile storage devices 102. The non-volatile storagedevice(s) 102 may comprise recording, memory, and/or storage devices,such as solid-state storage device(s), that are arranged and/orpartitioned into a plurality of addressable media storage locations. Asused herein, a media storage location refers to any physical unit ofmemory or storage (e.g., any quantity of physical storage medium on anon-volatile storage device 102). Memory units and/or storage units mayinclude, but are not limited to: pages, memory divisions, erase blocks,sectors, blocks, collections or sets of physical storage locations(e.g., logical pages, logical erase blocks, described below), or thelike.

The non-volatile storage controller may comprise an SML 130, which maypresent a logical address space 134 to one or more storage clients 116.One example of an SML is the Virtual Storage Layer® of SanDiskCorporation of Milpitas, Calif. Alternatively, each non-volatile storagedevice 102 may comprise a non-volatile storage medium controller 104,which may present a logical address space 134 to the storage clients116. As used herein, a logical address space 134 refers to a logicalrepresentation of memory resources, storage resources, or the like. Thelogical address space 134 may comprise a plurality (e.g., range) oflogical identifiers, logical addresses, or the like. As used herein, alogical identifier or logical address refers to a unique representationfor referencing a data structure, a memory resource, and/or a storageresource (e.g., data, a transaction log), including, but not limited to:a logical block address (LBA), cylinder/head/sector (CHS) address, afile name, an object identifier, an inode, a Universally UniqueIdentifier (UUID), a Globally Unique Identifier (GUID), a hash code, asignature, an index entry, a range, an extent, or the like.

The SML 130 may maintain metadata 135, such as a forward index or otherlogical-to-physical address mapping structure, to map logical addressesof the logical address space 134 to media storage locations on thenon-volatile storage device(s) 102. The SML 130 may provide forarbitrary, any-to-any mappings from logical addresses to physicalstorage resources. An “any-to any” mapping may map any logical addressto any physical storage resource. Accordingly, there may be nopre-defined and/or pre-set mappings between logical addresses andparticular, media storage locations and/or media addresses. A mediaaddress may refer to an address of a storage resource that uniquelyidentifies one storage resource from another to a controller thatmanages a plurality of storage resources. By way of example, a mediaaddress may include, but is not limited to: the address of a mediastorage location, a physical storage unit, a collection of physicalstorage units (e.g., a logical storage unit), a portion of a storageunit (e.g., a logical storage unit address and offset, range, and/orextent), or the like. Accordingly, the SML 130 may map logical addressesto physical data resources of any size and/or granularity, which may ormay not correspond to the underlying data partitioning scheme of thenon-volatile storage device(s) 102. For example, in some embodiments,the non-volatile storage controller 104, 130 is configured to store datawithin logical storage units that are formed by logically combining aplurality of physical storage units, which may allow the non-volatilestorage controller 104, 130 to support many different virtual storageunit sizes and/or granularities.

A logical storage element may refer to a set of two or more non-volatilestorage elements that are or are capable of being managed in parallel(e.g., via an I/O and/or control bus). A logical storage element maycomprise a plurality of logical storage units, such as logical pages,logical storage divisions (e.g., logical erase blocks), and so on. Alogical storage unit may refer to a logical construct combining two ormore physical storage units, each physical storage unit on a respectivenon-volatile storage element in the respective logical storage element(e.g., each non-volatile storage element being accessible in parallel).A logical storage division may refer to a set of two or more physicalstorage divisions, each physical storage division on a respectivenon-volatile storage element in the respective logical storage element.

The logical address space 134 presented by the SML 130 may have alogical capacity, which may correspond to the number of availablelogical addresses in the logical address space 134 and the size and/orgranularity of the data referenced by the logical addresses. Forexample, the logical capacity of a logical address space 134 comprising2̂32 unique logical addresses, each referencing 2048 bytes (2KiB) of datamay be 2̂43 bytes. A kibibyte (KiB) may refer to 1024 bytes. In someembodiments, the logical address space 134 may be thinly provisioned. A“thinly provisioned” logical address space 134 may refer to a logicaladdress space 134 having a logical capacity that exceeds the physicalcapacity of the underlying non-volatile storage device(s) 102. Forexample, the SML 130 may present a 64-bit logical address space 134 tothe storage clients 116 (e.g., a logical address space 134 referenced by64-bit logical addresses), which may exceed the physical capacity of theunderlying non-volatile storage devices 102. The large logical addressspace 134 may allow storage clients 116 to allocate and/or referencecontiguous ranges of logical addresses, while reducing the chance ofnaming conflicts. The SML 130 may leverage the any-to-any mappingsbetween logical addresses and physical storage resources to manage thelogical address space 134 independently of the underlying physicalstorage devices 102. For example, the SML 130 may add and/or removephysical storage resources seamlessly, as needed, and without changingthe logical addresses used by the storage clients 116.

In some embodiments, the non-volatile storage controller 104, 130 may beconfigured to store data on one or more asymmetric, write-once medium122, such as NAND flash or other solid-state storage media. As usedherein, a “write once” storage medium refers to a storage medium that isreinitialized (e.g., erased) each time new data is written or programmedthereon. As used herein, an “asymmetric” storage medium refers to astorage medium 122 having different latencies for different storageoperations. Many types of solid-state storage media are asymmetric; forexample, a read operation may be much faster than a write/programoperation, and a write/program operation may be much faster than anerase operation (e.g., reading the media may be hundreds of times fasterthan erasing, and tens of times faster than programming the media).

The storage medium 122 may be partitioned into storage divisions thatcan be erased as a group (e.g., erase blocks) in order to, inter alia,account for the asymmetric properties of the medium 122 or the like. Assuch, modifying a single data segment in-place may require erasing theentire erase block comprising the data, and rewriting the modified datato the erase block, along with the original, unchanged data. This mayresult in inefficient “write amplification,” which may excessively wearthe medium 122. Therefore, in some embodiments, the non-volatile storagecontroller 104, 130 may be configured to write data out-of-place. Asused herein, writing data “out-of-place” refers to writing data todifferent media storage location(s) rather than overwriting the data“in-place” (e.g., overwriting the original physical location of thedata). Modifying data out-of-place may avoid write amplification, sinceexisting, valid data on the erase block with the data to be modifiedneed not be erased and recopied. Moreover, writing data out-of-place mayremove erasure from the latency path of many storage operations (e.g.,the erasure latency is no longer part of the critical path of a writeoperation).

The non-volatile storage controller 104, 130 may comprise one or moreprocesses that operate outside of the regular path for servicing ofstorage operations (e.g., the “path” for performing a storage operationand/or servicing a storage request). As used herein, the “path forservicing a storage request” or “path for servicing a storage operation”(also referred to as the “critical path”) refers to a series ofprocessing operations needed to service the storage operation orrequest, such as a read, write, modify, or the like. The path forservicing a storage request may comprise receiving the request from astorage client 116, identifying the logical addresses of the request,performing one or more storage operations on non-volatile storage medium122, and returning a result, such as acknowledgement or data. Processesthat occur outside of the path for servicing storage requests mayinclude, but are not limited to: a groomer (e.g., garbage collection orother storage capacity recovery), de-duplication, and so on. Theseprocesses may be implemented autonomously and in the background, so thatthey do not interfere with or impact the performance of other storageoperations and/or requests. Accordingly, these processes may operateindependent of servicing storage requests.

In some embodiments, the non-volatile storage controller 104, 130comprises a groomer, which is configured to reclaim storage divisions(e.g., logical or physical erase blocks) for reuse, using a garbagecollection or other storage capacity recovery process. The writeout-of-place paradigm implemented by the non-volatile storage controller104, 130 may result in obsolete or invalid data remaining on thenon-volatile storage medium 122. For example, overwriting data X withdata Y may result in storing Y on a new storage division (e.g., ratherthan overwriting X in place), and updating the any-to-any mappings ofthe metadata to identify Y as the valid, up-to-date version of the data.The obsolete version of the data X may be marked as invalid, but may notbe immediately removed (e.g., erased), since, as discussed above,erasing X may involve erasing an entire storage division, which is atime-consuming operation and may result in write amplification.Similarly, data that is no longer is use (e.g., deleted or trimmed data)may not be immediately removed. The non-volatile storage medium 122 mayaccumulate a significant amount of invalid data.

A groomer process may operate outside of the critical path for servicingstorage operations. The groomer process may reclaim storage divisions sothat they can be reused for other storage operations. As used herein,reclaiming a storage division refers to erasing the storage division sothat new data may be stored/programmed thereon. Reclaiming a storagedivision may comprise relocating valid data on the storage division to anew location. The groomer may identify storage divisions for reclamationbased upon one or more factors, which may include, but are not limitedto: the amount of invalid data in the storage division, the amount ofvalid data in the storage division, wear on the storage division (e.g.,number of erase cycles), time since the storage division was programmedor refreshed, and so on.

The non-volatile storage controller 104, 130 may be further configuredto store data in a log format. A log format is one example of atransaction log, as described in greater detail below. As describedabove, a log format refers to a data format that defines an orderedsequence of storage operations performed on a non-volatile storagemedium 122. In some embodiments, the log format comprises storing datain a pre-determined sequence of media addresses of the non-volatilestorage medium 122 (e.g., within sequential pages and/or erase blocks ofthe medium 122). The log format may further comprise associating data(e.g., each packet or data segment) with respective sequence indicators.The sequence indicators may be applied to data individually (e.g.,applied to each data packet) and/or to data groupings (e.g., packetsstored sequentially on a storage division, such as an erase block). Insome embodiments, sequence indicators may be applied to storagedivisions when the storage divisions are reclaimed (e.g., erased), asdescribed above, and/or when the storage divisions are first used tostore data.

In some embodiments the log format may comprise storing data in an“append only” paradigm. The non-volatile storage controller 104, 130,using the log storage module 137 described below or the like, maymaintain a current append point at a media address of the non-volatilestorage device 102. The append point may be a current storage divisionand/or offset within a storage division. Data may then be sequentiallyappended from the append point. The sequential ordering of the data,therefore, may be determined based upon the sequence indicator of thestorage division of the data in combination with the sequence of thedata within the storage division. Upon reaching the end of a storagedivision, the non-volatile storage controller 104, 130 may identify the“next” available storage division (e.g., the next storage division thatis initialized and ready to store data). The groomer may reclaim storagedivisions comprising invalid, stale, and/or deleted data, to ensure thatdata may continue to be appended to the media log.

The log format described herein may allow valid data to be distinguishedfrom invalid data based upon the contents of the non-volatile storagemedium 122, and independently of other metadata. As discussed above,invalid data may not be removed from the non-volatile storage medium 122until the storage division comprising the data is reclaimed. Therefore,multiple “versions” of data having the same context may exist on thenon-volatile storage medium 122 (e.g., multiple versions of data havingthe same logical addresses). The sequence indicators associated with thedata may be used to distinguish invalid versions of data from thecurrent, up-to-date version of the data; the data that is the mostrecent in the log is the current version, and previous versions may beidentified as invalid.

The storage management layer 130 may be configured to provide storageservices to one or more storage clients 116. As described above, storageclients 116 may include local storage clients 116 operating on thecomputing device 110 and/or remote, storage clients 116 accessible viathe network 115 and/or network interface 113. The storage clients 116may include, but are not limited to: operating systems, file systems,database systems 116 a, server applications, kernel-level processes,user-level processes, applications, or the like.

The storage management layer 130 comprises and/or is communicativelycoupled to one or more non-volatile storage devices 102, 121. The one ormore non-volatile storage devices 102, 121 may include different typesof non-volatile storage devices including, but not limited to:solid-state storage devices, hard drives, tape drives, SAN storageresources, or the like. The one or more non-volatile storage devices 102may comprise one or more respective non-volatile storage mediumcontrollers 104 and non-volatile storage media 122. As illustrated inFIG. 1, The SML 130 may provide access to the one or more non-volatilestorage devices 102, 121 via a traditional block I/O interface 131.Additionally, the SML 130 may provide access to enhanced functionality(e.g., a large, virtual address space 134) through the SML interface132. The metadata 135 may be used to manage and/or track storageoperations performed through any of the Block I/O interface 131, SMLinterface 132, cache interface, auto-commit memory (ACM) interface 133,or other, related interfaces.

The cache interface may expose cache-specific features accessible viathe storage management layer 130. Also, in some embodiments, the SMLinterface 132 presented to the storage clients 116 provides access todata transformations implemented by the one or more non-volatile storagedevices 102 and/or the one or more non-volatile storage mediumcontrollers 104.

The SML 130 may provide storage services through one or more interfaces,which may include, but are not limited to: a block I/O interface, an ACMinterface 133, an extended storage management layer interface, a cacheinterface, and the like. The SML 130 may present a logical address space134 to the storage clients 116 through one or more interfaces. Asdiscussed above, the logical address space 134 may comprise a pluralityof logical addresses, each corresponding to respective media locationsthe on one or more non-volatile storage devices 102. The SML 130 maymaintain metadata 135 comprising any-to-any mappings between logicaladdresses and media locations, as described above.

The SML 130 may further comprise a non-volatile storage device interface139 configured to transfer data, commands, and/or queries to the one ormore non-volatile storage devices 102, 121 over the network 115, over abus, which may include, but is not limited to: a peripheral componentinterconnect express (PCI Express or PCIe) bus, a serial AdvancedTechnology Attachment (ATA) bus, a parallel ATA bus, a small computersystem interface (SCSI), FireWire, Fibre Channel, a Universal Serial Bus(USB), a PCIe Advanced Switching (PCIe-AS) bus, a network 115,Infiniband, SCSI RDMA, or the like. The non-volatile storage deviceinterface 139 may communicate with the one or more non-volatile storagedevices 102, 121 using input-output control (IO-CTL) command(s), IO-CTLcommand extension(s), remote direct memory access, or the like. While asingle non-volatile storage device interface 139 is depicted, in furtherembodiments, the SML 130 may comprise different interfaces 139 for thenon-volatile storage device 102 including the volatile memory 1013(e.g., auto-commit memory) and for the second non-volatile storagedevice 121.

The communication interface 113 may comprise one or more networkinterfaces configured to communicatively couple the computing device 110and/or the non-volatile storage controller 104, 130 to a network 115and/or to one or more remote, network-accessible storage clients 116.The storage clients 116 may include local storage clients 116 operatingon the computing device 110 and/or remote, storage clients 116accessible via the network 115 and/or the network interface 113. Thenon-volatile storage controller 104, 130 comprises and/or is incommunication with one or more non-volatile storage devices 102, 121.Although FIG. 1 depicts a single non-volatile storage device 102comprising a volatile memory 1013, the disclosure is not limited in thisregard and could be adapted to incorporate any number of non-volatilestorage devices 102 comprising a volatile memory 1013, of additionalnon-volatile storage devices 121, or the like.

The non-volatile storage device 102 and/or the second non-volatilestorage device 121 may comprise one or more non-volatile storage media122, which may include but is not limited to: NAND flash memory, NORflash memory, nano random access memory (nano RAM or NRAM), nanocrystalwire-based memory, silicon-oxide based sub-10 nanometer process memory,graphene memory, Silicon-Oxide-Nitride-Oxide-Silicon (SONOS), resistiveRAM (RRAM), programmable metallization cell (PMC), conductive-bridgingRAM (CBRAM), magneto-resistive RAM (MRAM), battery backed dynamic RAM(DRAM) and/or static random-access memory (SRAM), phase change RAM (PRAMor PCM), ferroelectric RAM (F-RAM), magnetic storage medium (e.g., harddisk, tape), optical storage medium, or the like. While the non-volatilestorage medium 122 is referred to herein as “storage media,” in variousembodiments, the non-volatile storage medium 122 may more generallycomprise a non-volatile recording medium capable of recording data,which may be referred to as a non-volatile memory medium, a non-volatilestorage medium, or the like. Further, the non-volatile storage device102, in various embodiments, may comprise a non-volatile recordingdevice, a non-volatile memory device, a non-volatile storage device, orthe like.

The non-volatile storage medium 122 may comprise one or morenon-volatile storage elements 123, which may include, but are notlimited to: chips, packages, die planes, die, and the like. Anon-volatile storage medium controller 104 may be configured to managestorage operations on the non-volatile storage medium 122, and maycomprise one or more processors, programmable processors (e.g.,field-programmable gate arrays), or the like. In some embodiments, thenon-volatile storage medium controller 104 is configured to store dataon and/or read data from the non-volatile storage medium 122 in thecontextual, log format described above, and to transfer data to/from thenon-volatile storage device 102, and so on.

The non-volatile storage medium controller 104 may be communicativelycoupled to the non-volatile storage medium 122 and/or the volatilememory 1013 by way of one or more buses 127 (e.g., a memory bus, acontrol bus, a communications bus). The bus 127 may comprise an I/O busfor communicating data to/from the non-volatile storage elements 123.The bus 127 may further comprise a control bus for communicatingaddressing and other command and control information to the non-volatilestorage elements 123. In some embodiments, the bus 127 maycommunicatively couple the non-volatile storage elements 123 to thenon-volatile storage medium controller 104 in parallel. This parallelaccess may allow the non-volatile storage elements 123 to be managed asa group, forming a logical storage element 129. As discussed above, thelogical storage element may be partitioned into respective logicalstorage units (e.g., logical pages) and/or logical storage divisions(e.g., logical erase blocks). The logical storage units may be formed bylogically combining physical storage units of each of the non-volatilestorage elements. For example, if the non-volatile storage medium 122comprises twenty-five (25) non-volatile storage elements, each logicalstorage unit may comprise twenty-five (25) pages (e.g., a page of eachelement of non-volatile storage medium 122).

A non-volatile storage controller (e.g., hardware and/or software forcontrolling the non-volatile storage device 102 and/or the secondnon-volatile storage device 121) may comprise an SML 130 and/or thenon-volatile storage medium controller 104. The SML 130 may providestorage services to the storage clients 116 via one or more interfaces131, 132, and/or 133. In some embodiments, the SML 130 provides ablock-device I/O interface 131 through which storage clients 116 performblock-level I/O operations. Alternatively, or in addition, the SML 130may provide a storage management layer (SML) interface 132, which mayprovide other storage services to the storage clients 116. In someembodiments, the SML interface 132 may comprise extensions to the blockdevice interface 131 (e.g., storage clients 116 may access the SMLinterface 132 through extensions to the block device interface 131). TheSML 130 may comprise an ACM interface 133 for storing data in thevolatile memory 1013, while ensuring persistence of the data in thenon-volatile storage medium 122, as described below. Alternatively, orin addition, the SML interface 132 may be provided as a separate API,service, and/or library. The SML 130 may be further configured toprovide a cache interface for caching data using the non-volatilestorage system 100.

As described in greater detail below, in certain embodiments, a storageclient 116 may be aware of and/or configured to use the volatile memory1013 of the non-volatile storage device 102. For example, a databasesystem storage client 116 a may comprise at least a portion of theacceleration module 150, and may be configured to send one or moredatabase log entries or other transaction log entries to the volatilememory 1013 of the non-volatile storage device 102 (e.g., using one ormore addresses of the logical address space 134 of the non-volatilestorage device 102 or the like).

In a further embodiment, a storage client 116 may not be aware of and/orconfigured to use the volatile memory 1013 of the non-volatile storagedevice 102, and the acceleration module 150 may filter and/or rerouteone or more transaction log entries, such as database log entries, whichthe storage client 116 has sent to another location, such as the secondnon-volatile storage device 121, to the volatile memory 1013 of thenon-volatile storage device 102. Once the volatile memory 1013 stores afiltered and/or rerouted transaction log entry, in certain embodiments,the acceleration module 150 may store the transaction log entry in theoriginal location to which the entry was sent, such as the secondnon-volatile storage device 121. In this manner, in certain embodiments,the acceleration module 150 may accelerate storage of a transaction log,operation of a storage client 116, or the like transparently, withlittle or no cooperation from the storage client 116 itself.

As described above, the SML 130 may present a logical address space 134to the storage clients 116 (e.g., through the interfaces 131, 132,and/or 133). The SML 130 may maintain metadata 135 comprising any-to-anymappings between logical addresses in the logical address space 134 andmedia locations on the non-volatile storage device 102. The metadata 135may comprise a logical-to-physical mapping structure with entries thatmap logical addresses in the logical address space 134 and medialocations on the non-volatile storage device 102. Thelogical-to-physical mapping structure of the metadata 135, in oneembodiment, is sparsely populated, with entries for logical addressesfor which the non-volatile storage device 102 stores data and with noentries for logical addresses for which the non-volatile storage device102 does not currently store data. The metadata 135, in certainembodiments, tracks data at a block level, with the SML 130 managingdata as blocks.

The non-volatile storage system 100 may further comprise a log storagemodule 137, which, as described above, may be configured to store dataon the non-volatile storage device 102 in a contextual, log format. Thecontextual, log data format may comprise associating data with a logicaladdress on the non-volatile storage medium 122. The contextual, logformat may further comprise associating data with respective sequenceidentifiers on the non-volatile storage medium 122, which define anordered sequence of storage operations performed on the non-volatilestorage medium 122, as described above. The non-volatile storagecontroller may further comprise a non-volatile storage device interface139 that is configured to transfer data, commands, and/or queries to thenon-volatile storage medium controller 104 over the network 115, asdescribed above.

In certain embodiments, the system 100 (e.g., the non-volatile storagedevice 102) preserves data and/or provides power management even in theevent of a power failure, power reduction, power loss, impropershutdown, restart event, or other trigger. The non-volatile storagedevice 102, in the depicted embodiment, has a primary power connection136 that connects the non-volatile storage device 102 to a primary powersource that provides the non-volatile storage device 102 with power toperform data storage operations such as reads, writes, erases, or thelike.

The non-volatile storage device 102, under normal operating conditionsor the like, may receive electric power from a primary power source overthe primary power connection 136. In certain embodiments, the primarypower connection 136 may connect the non-volatile storage device 102 toan external power supply, such as an electrical outlet, a powerconverter (e.g., a power brick), an uninterruptable power supply (UPS),an electrical generator, a battery, or another power source. In afurther embodiment, the primary power connection 136 may be integratedwith a network 115 connection, such as power over Ethernet (PoE) or thelike.

In other embodiments, the primary power connection 136 connects thenon-volatile storage device 102 to the host computing device 110, andthe host computing device 110 acts as the primary power source thatsupplies the non-volatile storage device 102 with power. In certainembodiments, the primary power connection 136 may comprise or beintegrated with a communications connection, such as a PCI connection, aPCIe connection, or the like.

The non-volatile storage device 102, in certain embodiments, implementsa write data pipeline 106 and a read data pipeline 108, an example ofwhich is described in greater detail below with regard to FIG. 2. Thewrite data pipeline 106 may perform certain operations on data as thedata is transferred from the host computing device 110 into thenon-volatile storage medium 122. These operations may include, forexample, error correction code (ECC) generation, encryption,compression, and others. The read data pipeline 108 may perform similarand potentially inverse operations on data that is being read out ofnon-volatile storage medium 122 and sent to the host computing device110.

The non-volatile storage device 102, in the depicted embodiment,includes a secondary power supply 124. The secondary power supply 124may provide power to the non-volatile storage device 102 in response toa power level of the primary power connection 136 failing to satisfy athreshold (e.g., complete or partial power disruption) resulting in thenon-volatile storage device 102 not receiving enough electrical powerover the primary power connection 136, and/or in response to anothertrigger. A power disruption may be an event that causes the non-volatilestorage device 102 to stop receiving power over the primary powerconnection 136, causes a reduction in power the non-volatile storagedevice 102 receives over the primary power connection 136, causes powerfrom the primary power connection 136 to fall below a predefinedthreshold, or the like. A predefined threshold for power received overthe primary power connection 136, in certain embodiments, may beselected to allow for normal fluctuations in the level of power from theprimary power connection 136.

For example, a power disruption may occur in response to the power in abuilding where the non-volatile storage device 102 is located failing or“going out.” In various embodiments, a user action such as unplugging orimproperly shutting down the non-volatile storage device 102, a failurein the primary power connection 136, a failure in the primary powersupply, or the like may cause a power disruption. Numerous, varied powerdisruptions may cause unexpected power loss for the non-volatile storagedevice 102.

The secondary power supply 124 may include one or more batteries, one ormore capacitors, a bank of capacitors, a separate connection to a powersupply, or another path or source different than the primary powerconnection 136. In one embodiment, the secondary power supply 124provides power to the non-volatile storage device 102 for at least apower hold-up time during a power disruption or other reduction in powerfrom the primary power connection 136, or in response to anothertrigger. The secondary power supply 124, in a further embodiment,provides a power hold-up time long enough to enable the non-volatilestorage device 102 to flush data that is not yet stored in non-volatilestorage medium 122 from the volatile memory 1013 into the non-volatilestorage medium 122.

As a result, the non-volatile storage device 102 may preserve data thatis not permanently stored in the non-volatile storage device 102 (e.g.,data stored in the volatile memory 1013) before a lack of power causesthe non-volatile storage device 102 to stop functioning. In certainembodiments, the secondary power supply 124 may comprise the smallestcapacitors possible that are capable of providing a predefined powerhold-up time, thereby preserving space, reducing cost, and/orsimplifying the non-volatile storage device 102. In one embodiment, oneor more banks of capacitors are used to implement the secondary powersupply 124. For example, capacitors may be more reliable, require lessmaintenance, and/or have a longer life than batteries or other optionsfor providing secondary power.

In one embodiment, the secondary power supply 124 is part of anelectrical circuit that automatically provides power to the non-volatilestorage device 102 upon a partial or complete loss of power from theprimary power connection 136, or in response to another trigger.Similarly, the system 100 may be configured to automatically accept orreceive electric power from the secondary power supply 124 during apartial or complete power loss. For example, in one embodiment, thesecondary power supply 124 may be electrically coupled to thenon-volatile storage device 102 in parallel with the primary powerconnection 136, so that the primary power connection 136 charges thesecondary power supply 124 during normal operation and the secondarypower supply 124 automatically provides power to the non-volatilestorage device 102 in response to a power loss, power failing to satisfya threshold, or another trigger. In one embodiment, the system 100further includes a diode or other reverse current protection between thesecondary power supply 124 and the primary power connection 136, toprevent current from the secondary power supply 124 from reaching theprimary power connection 136. In another embodiment, the non-volatilestorage device 102 (e.g., using the auto-commit memory 1011 describedbelow) may enable or connect the secondary power supply 124 to thenon-volatile storage device 102 using a switch or the like in responseto power from the primary power connection 136 failing to satisfy athreshold and/or another trigger.

Examples of data that is not yet stored in the non-volatile storagemedium 122 may include data stored in the volatile memory 1013, “inflight” data held in volatile memory as the data moves through a writedata pipeline 106 to be stored in the non-volatile storage medium 122,or the like. If data in the volatile memory 1013, in a write datapipeline 106, or the like is lost during a power outage or due toanother trigger (e.g., is not written to the non-volatile storage medium122 or otherwise permanently stored), data corruption and/or data lossmay result.

In certain embodiments, the non-volatile storage device 102 sends anacknowledgement to the host computing device 110 at some point after thenon-volatile storage device 102 receives data to be stored in thenon-volatile storage medium 122. A write data pipeline 106, or asub-component thereof, may generate the acknowledgement. It may beadvantageous for the non-volatile storage device 102 to send anacknowledgement as soon as possible after receiving the data, but notuntil the non-volatile storage device 102 may ensure persistence of thereceived data.

In certain embodiments, the non-volatile storage medium controller 104(e.g., a write data pipeline 106) sends an acknowledgement for databefore the data is actually stored in the non-volatile storage medium122. For example, the non-volatile storage medium controller 104 maysend an acknowledgement for data in response to the volatile memory 1013storing the data, in response to the volatile memory 1013 being armedwith metadata to commit the data to the non-volatile storage medium 122,or the like, as described below. In such embodiments, it may bedesirable that the non-volatile storage device 102 persist data (e.g.,store the data in the non-volatile storage medium 122) for which thestorage controller 104 has sent an acknowledgement before the secondarypower supply 124 loses power, in order to prevent data corruption andensure the integrity of the acknowledgement sent.

As described below, the volatile memory 1013 may comprise an auto-commitmemory 1011. In certain embodiments, the volatile memory 1013 is incommunication with, managed by, and/or at least partially integratedwith the storage controller 104. In one embodiment, the non-volatilestorage medium controller 104 (e.g., the auto-commit memory 1011)initiates a power loss mode in the non-volatile storage device 102 inresponse to a power from the primary power connection 136 failing tosatisfy a threshold, or in response to another trigger.

During the power loss mode, the non-volatile storage medium controller104 (e.g., auto-commit memory 1011), in one embodiment, flushes datathat is in the non-volatile storage device 102 (e.g., stored in thevolatile memory 1013) that is not yet stored in non-volatile storagemedium 122 into the non-volatile storage medium 122. In certainembodiments, the non-volatile storage medium controller 104 (e.g.,auto-commit memory 1011) may adjust execution of data operations on thenon-volatile storage device 102 to ensure that essential operationscomplete before the secondary power supply 124 loses sufficient power tocomplete the essential operations (e.g., during a power hold-up timethat the secondary power supply 124 provides).

In certain embodiments, essential operations comprise those operationsfor data that has been acknowledged as having been stored, such asacknowledged write operations, write operations for data stored in thevolatile memory 1013, or the like. In other embodiments, essentialoperations comprise those operations for data that has been acknowledgedas having been stored and for data that has been acknowledged as erased.In other embodiments, essential operations comprise those operations fordata that have been acknowledged as having been stored, as having beenread, and/or as having been erased. The non-volatile storage mediumcontroller 104 (e.g., auto-commit memory 1011) may terminatenon-essential operations to ensure that those non-essential operationsdo not consume power unnecessarily and/or do not block essentialoperations from executing. For example, the non-volatile storage mediumcontroller 104 (e.g., auto-commit memory 1011) may terminate eraseoperations, read operations, unacknowledged write operations, or thelike to ensure that data stored in the volatile memory 1013 issuccessfully flushed to and stored in the non-volatile storage medium122.

In one embodiment, terminating non-essential operations preserves powerfrom the secondary power supply 124, allowing the secondary power supply124 to provide the power hold-up time. In a further embodiment, thenon-volatile storage medium controller 104 (e.g., auto-commit memory1011) quiesces or otherwise shuts down operation of one or moresubcomponents of the non-volatile storage device 102 during the powerloss mode to conserve power from the secondary power supply 124. Forexample, in various embodiments, the non-volatile storage mediumcontroller 104 (e.g., auto-commit memory 1011) may quiesce operation ofa read data pipeline 108, of a direct memory access (DMA) engine, and/orother subcomponents of the non-volatile storage device 102 that areassociated with non-essential operations.

In one embodiment, the system 100 includes one or more circuit boards,such as a motherboard or the like, that receive one or more adapters,such as a daughter card or the like, and each adapter receives one ormore storage devices 102. In a further embodiment, the adapters arecoupled to the circuit board using PCI-e slots of the circuit board andthe storage devices 102 are coupled to the adapters using PCI-e slots ofthe adapters. In another embodiment, the storage devices 102 eachcomprise a dual in-line memory module (DIMM) of non-volatile solid-statestorage media 122, such as Flash memory, or the like. In one embodiment,the circuit board, the adapters, and the storage devices 102 may beexternal to the host computing device 110 (e.g., located on the network115), and may include a separate primary power connection 136. Forexample, the circuit board, the one or more adapters, and the one ormore storage devices 102 may be housed in an external enclosure with apower supply unit (PSU) and may be in communication with the hostcomputing device 110 over the network 115; over an external bus such aseSATA, eSATAp, SCSI, FireWire, Fiber Channel, USB, PCIe-AS; or the like.

The systems, methods, and apparatuses described above may be leveragedto implement an auto-commit memory capable of implementing memorysemantic write operations (e.g., persistent writes) at or near CPUmemory write granularity and speed, over the network 115, or the like.By guaranteeing that certain commit actions for the write operationswill occur, even in the case of a power failure or other restart event,in certain embodiments, volatile memory 1013 such as DRAM, SRAM, BRAM,or the like, may be used as, considered as, and/or represented asnon-volatile.

The auto-commit memory described herein, may be configured to ensure orguarantee that data is preserved or persisted, even while the data isstored in the volatile memory 1013. The volatile memory 1013, elements,modules, or devices described herein, may be armed or associated withauto-commit metadata defining a commit action for the non-volatilestorage medium controller 104 (e.g., auto-commit memory 1011) to performin response to a trigger. A trigger, a commit trigger, a trigger event,a commit event, or the like for the non-volatile storage mediumcontroller 104 (e.g., auto-commit memory 1011), as used herein, maycomprise an occurrence, a system state, a condition, a request, or thelike, in response to which the non-volatile storage medium controller104 (e.g., auto-commit memory 1011) is configured to perform one or morecommit actions, such as flushing or preserving data from a volatilememory 1013 to the non-volatile storage medium 122. The non-volatilestorage medium controller 104 (e.g., auto-commit memory 1011), incertain embodiments, may flush, stream, copy, transfer, or destage datafrom the volatile memory 1013 without regard to any single specifictrigger event. For example, the non-volatile storage medium controller104 (e.g., auto-commit memory 1011) may destage data from the volatilememory 1013 to the non-volatile storage medium 122 to free space in thevolatile memory 1013, or the like.

In certain embodiments, a trigger for the non-volatile storage mediumcontroller 104 (e.g., auto-commit memory 1011) may comprise anon-failure, non-power-loss, and/or non-restart event during routineruntime of the system 100, such as a volatile memory 1013 bufferbecoming full, receiving a destage request, or the like. In otherembodiments, a trigger may comprise a failure condition, a power-losscondition, or other restart event. A restart event, as used herein,comprises an intentional or unintentional loss or reduction of power toat least a portion of the host computing device 110 and/or anon-volatile storage device 102. A restart event may comprise a systemreboot, reset, or shutdown event; a power fault, power loss, or powerfailure event; or another interruption or reduction of power. Byguaranteeing certain commit actions, the non-volatile storage mediumcontroller 104 (e.g., auto-commit memory 1011) may allow storage clients116 to retrieve data (e.g., transaction log entries), resume executionstates, or the like even after a restart event, may allow the storageclients 116 to persist different independent data sets, or the like.

As used herein, the term “memory semantic operations,” or moregenerally, “memory operations,” refers to operations having agranularity, synchronicity, and access semantics of volatile memoryaccesses, using manipulatable memory pointers, or the like. Memorysemantic operations may include, but are not limited to: load, store,peek, poke, write, read, set, clear, and so on. Memory semanticoperations may operate at a CPU-level of granularity (e.g., singlebytes, words, cache lines, or the like), and may be synchronous (e.g.,the CPU waits for the operation to complete). In certain embodiments,providing access at a larger sized granularity, such as cache lines, mayincrease access rates, provide more efficient write combining, or thelike than smaller sized granularity access.

The volatile memory 1013 may be available to computing devices 110and/or applications 116 (e.g., local on the computing device 110, remoteover the network 115, or the like) using one or more of a variety ofmemory mapping technologies, including, but not limited to, memorymapped I/O (MMIO), port I/O, port-mapped IO (PMIO), Memory mapped fileI/O, or the like. For example, the volatile memory 1013 may be availableto computing devices and/or applications (both local and remote) using aPCI-e Base Address Register (BAR), or other suitable mechanism. Thevolatile memory 1013 may also be directly accessible via a memory bus ofa CPU, using an interface such as a double data rate (DDR) memoryinterface, HyperTransport, QuickPath Interconnect (QPI), or the like.Accordingly, the volatile memory 1013 may be accessible using memoryaccess semantics, such as CPU load/store, direct memory access (DMA),3^(rd) party DMA, remote DMA (RDMA), atomic test and set, and so on. Thedirect, memory semantic access to the volatile memory 1013 disclosedherein allows many of the system and/or virtualization layer callstypically required to implement committed operations to be bypassed,(e.g., call backs via asynchronous Input/Output interfaces may bebypassed). In some embodiments, the volatile memory 1013 may be mappedto one or more virtual ranges (e.g., virtual BAR ranges, virtual memoryaddresses, or the like). The virtual mapping may allow multiplecomputing devices and/or applications to share a single ACM addressrange (e.g., access the same ACM simultaneously, within differentvirtual address ranges). The volatile memory 1013 may be mapped into anaddress range of a physical memory address space addressable by a CPU111 so that the CPU 111 may use load/store instructions to read andwrite data directly to the volatile memory 1013 using memory semanticaccesses. A CPU 111, in a further embodiment, may map the physicallymapped volatile memory 1013 into a virtual memory address space, makingthe volatile memory 1013 available to user-space processes or the likeas virtual memory.

The volatile memory 1013 may be pre-configured to commit its contentsupon detection of a restart condition (or other pre-determinedtriggering event) and, as such, operations performed on the volatilememory 1013 may be viewed as being “instantly committed.” For example,an application 116 may perform a “write-commit” operation on thevolatile memory 1013 using memory semantic writes that operate at ornear CPU memory granularity and speed, without the need for separatecorresponding “commit” commands, which may significantly increase theperformance of applications 116 affected by write-commit latencies. Asused herein, a write-commit operation may be an operation in which anapplication 116 writes data to a memory location (e.g., using a memorysemantic access), and then issues a subsequent commit command to committhe operation (e.g., to persistent storage or other commit mechanism).

Applications 116 whose performance is based on write-commit latency, thetime delay between the initial memory write and the subsequentpersistent commit operation, may attempt to reduce this latency byleveraging a virtual memory system (e.g., using a memory backed file).In this case, the application 116 may perform high-performance memorysemantic write operations in system RAM 112, but, in order to commit theoperations, must perform subsequent “commit” commands to persist eachwrite operation to the backing file (or other persistent storage).Accordingly, each write-commit operation may comprise its own separatecommit command. For example, in a database logging application, each logtransaction must be written and committed before a next transaction islogged. Similarly, messaging systems (e.g., store and forward systems)may write and commit each incoming message, before receipt of themessage can be acknowledged. The write-commit latency, therefore, maycomprise a relatively fast memory semantic write followed by a muchslower operation to commit the data to persistent storage. Write-commitlatency may include several factors including, access times topersistent storage, system call overhead (e.g., translations between RAMaddresses, backing store LBA, or the like), and so on. Examples ofapplications 116 that may benefit from reduced write-commit latencyinclude, but are not limited to: database logging applications (e.g., adatabase system 116), file system logging, messaging applications (e.g.,store and forward), semaphore primitives, or the like.

The systems, apparatuses, and methods for transaction log accelerationusing auto-commit memory disclosed herein may be used to increase theperformance of write-commit latency bound applications 116 by providingdirect access to a memory region at any suitable level of addressinggranularity including byte level, page level, cache-line level, or othermemory region level, that may be guaranteed to be committed in the eventof a system failure or other restart event, without the application 116issuing a separate commit command. Accordingly, the write-commit latencyof an application 116 may be reduced to the latency of a memory semanticaccess (e.g., a single write over a system bus, an RDMA transaction overthe network 115, an Infiniband transaction, or the like).

The acceleration module 150, in certain embodiments, may use orcooperate with the volatile memory 1013, as described herein, to providetransaction log acceleration to clients 116 (e.g., a database system, anoperating system, virtual operating platform, guest operating system,application, process, thread, entity, utility, user, or the like) withmany of the benefits and speed of volatile memory 1013 and thepersistence of the non-volatile storage medium 122.

A data structure, as used herein, comprises an organized arrangement,group, or set of data. A data structure may be organized according to apredefined pattern or schema, may comprise metadata such as pointers,sequence numbers, labels, identifiers, or the like to facilitateorganization of and access to the included data. Data structures mayinclude, but are not limited to, a log (e.g., a transaction log, asequential log, an application log, a database log, a binary log, anaudit trail, a journal, a transaction journal, a database journal, alinked list), a queue (e.g., a first-in-first-out or FIFO queue, abuffer), a stack (e.g. a last-in-first-out or LIFO stack), a tree (e.g.,a binary tree, B-tree, B+ tree, B* tree, ternary tree, K-ary tree,space-partitioning tree, decision tree), a linked-list (e.g., singlylinked list, doubly linked list, self-organizing list, doubly connectededge list), a hash (e.g., a hash list, hash table, hash tree, hasharray), an array (e.g., a table, map, bit array, bit field, bitmap,matrix, sparse array), a heap (e.g., a binary heap, binomial heap,Fibonacci heap, ternary heap, D-ary heap), a graph (e.g., directedgraph, directed acyclic graph, binary decision diagram, graph-structuredstack, multigraph, hypergraph, adjacency list), or other data structure.

One example of a data structure is a transaction log (TLOG). As usedherein, a transaction log may comprise a data structure that includes anordered sequence of entries. A transaction log (e.g., a sequential log,an application log, a database log, a binary log, an audit trail, ajournal, a transaction journal, a database journal, a linked list), incertain embodiments, includes sequential, historical, or chronologicalentries, such as a history or list of updates made to a database system116 a or database table, transactions executed by and/or on a databasesystem 116 a or other application 116, or the like. A transaction logentry or record may include enough information regarding eachtransaction to either rollback or undo the transaction, or to redo orreapply the transaction. For example, an entry or record of atransaction log such as a database log may include an update log record(e.g., recording an update or change in a database system 116 a or otherstorage client 116), a compensation log record (e.g., recording therollback of a change in a database system 116 a or other storage client116), a commit record (e.g., recording a decision to commit atransaction), an abort record (e.g., recording a decision to abortand/or roll back a transaction), a checkpoint record (e.g., recordingthat a checkpoint has been made, to accelerate recovery or the like), acompletion record (e.g., recording that a transaction is complete, hasbeen fully committed, aborted, or the like).

In addition to or instead of being stored sequentially orchronologically, in certain embodiments, a transaction log may includesequence information for each entry or transaction, such as a timestamp,a sequence number, a link to a previous or next entry, or the like. Atransaction log may also include other types of metadata, such as atransaction identifier (e.g., a reference to a database transaction thatgenerated the log record), a type (e.g., a label describing the type ofdatabase log record), or the like. While a transaction log is primarilydescribed herein with regard to the acceleration module 150, thedescription is equally applicable to other types of data structures,such as the example data structures listed above.

The acceleration module 150 may provide an interface, such as anapplication programming interface (API), shared library, hardwareinterface, a communications bus, one or more IO control (IOCTL)commands, a network interface, or the like, over which a client 116 maycreate, update, delete, or otherwise access one or more types oftransaction log data structures. In certain embodiments, a client 116,such as a database system 116 a, may be unaware of the non-volatilestorage device 102 and/or the auto-commit memory 1011, and theacceleration module 150 and/or the SML 130 may filter or intercepttransaction log entries from the client 116, so that the client 116 doesnot access the interface of the acceleration module 150 directly.

A data structure, in certain embodiments, is persistent if the datastructure remains accessible to a client 116 in some form after arestart event or other trigger, which may be ensured or guaranteed bythe non-volatile storage medium controller 104 (e.g., auto-commit memory1011), as described herein. The acceleration module 150 may associate apersistent logical identifier with a transaction log data structureand/or with a client 116 (e.g., a database system 116 a), which theclient 116 may use to access the transaction log data structure bothbefore and after a restart event. For example, the acceleration module150 may cooperate with a file system module 1558 as described below withregard to FIG. 4 to provide access to a transaction log data structureas a file system file with a filename, a filename and an offset, or thelike. In other embodiments, a persistent logical identifier may comprisea logical unit number (LUN) identifier (ID) from a LUN namespace, a LUNID and an offset, a logical identifier for a persistent memory namespacefor the ACM 1011 as described below, a logical block address (LBA) orLBA range from a namespace of the non-volatile storage device 102, oranother persistent logical identifier.

To make efficient use of the volatile memory 1013, which may have asmaller storage capacity than the non-volatile storage medium 122, andto provide the access speed of the volatile memory 1013 and thepersistence of the non-volatile storage medium 122, as a client 116writes data to a transaction log data structure (e.g., in theforeground) at an input rate, the acceleration module 150 may cooperatewith the ACM 1011 to destage, copy, transfer, migrate, and/or move datafrom volatile memory buffers 1013 to the non-volatile storage medium 122and/or to the non-volatile storage device 121 (e.g., in the background)at a transfer rate that matches or exceeds the input rate over time, sothat the data does not overrun the one or more volatile memory buffers1013 allocated to the transaction log data structure. The accelerationmodule 150, in one embodiment, may block, delay, throttle, govern, orotherwise limit the input rate at which a client 116 writes data to atransaction log data structure. In this manner, the acceleration module150 may mask or hide the volatile memory 1013 and/or non-volatilestorage medium 122 from a client 116 such that the client 116 perceivesthe access speed and benefits of the volatile memory 1013 and thepersistence of the non-volatile storage medium 122, without being awareof the complexities of the tiered architecture that the accelerationmodule 150 uses to provide these benefits.

The acceleration module 150, in certain embodiments, may enforce one ormore rules for a data structure (e.g., a transaction log). For example,each different type of data structure may be defined or structured by aset of one or more rules, restrictions, definitions, or the like. Therules may define one or more allowed or acceptable data operations for adata structure. For a transaction log, the rules may include thatentries must be sequential, that data entries may not be overwritten orupdated once written, or the like. Different types of data structuresmay have different rules. For example, a queue may have a strict FIFOrule, a stack may have a strict LIFO rule, a tree may have a ruledefining a strict order or hierarchy for data entries or nodes, a datastructure may have a rule requiring certain data types or requiredfields or entries, or the like.

In certain embodiments, by providing an interface that enforces one ormore rules for a data structure, the acceleration module 150 may preventan application 116 or other client 116 from inadvertently or accidentlyoverwriting or otherwise violating the integrity of a transaction logdata structure, ensuring that the transaction log data structuresatisfies the data structure's strict definition, or the like. Becausethe acceleration module 150 may provide data structures that arenon-volatile or persistent, errors in data structure integrity (e.g., anoverwritten data structure, an improper entry in a data structure, orthe like) may otherwise persist after a restart event or reboot, andwould not be cleared or reset as would errors in a volatile datastructure.

The acceleration module 150, in certain embodiment, may provide aninterface or library that integrates with and/or provides an operatingsystem, a file system, one or more applications, a database system 116a, or other clients 116 access to the hardware capabilities of thevolatile memory 1013 and/or the non-volatile storage medium 122 in asubstantially transparent manner, thereby providing transaction log datastructures accessible via a library, a filename or other persistentlogical identifier, or the like. Because the acceleration module 150manages the tiered hierarchy of the volatile memory 1013, thenon-volatile storage medium 122 (e.g., the storage management layer130), a file system (e.g., the file system module 1558 described below),in one embodiment, the acceleration module 150 may provide the benefitsof the ACM 1011 for transaction log acceleration, even with a smallamount of volatile memory 1013 for the ACM 1011 relative to storagecapacity of the non-volatile storage medium 122.

In certain embodiments, the acceleration module 150 may providesubstantially transparent integration of transaction log data structureswith a file system. For example, a client 116 may access a transactionlog data structure using file system semantics, as a file with afilename, using a filename and an offset, or the like, while theacceleration module 150 manages the transfer of data of the datastructure between the ACM buffers 1013 (e.g., volatile memory 1013,volatile memory buffers 1013, volatile memory modules 1013, volatilememory elements 1013, volatile memory pages 1013) of the ACM 1011 andthe non-volatile storage medium 122, may enforce one or more rules forthe data structure (e.g., prevent a file for a data structure from beingoverwritten, ensure a file for a data structure is append-only, ensureentries of a file for a data structure are sequential, or the like), sothat the client 116 is spared such responsibilities. In this manner, anapplication 116 or other client 116 may receive the benefits of theacceleration module 150 and/or the ACM 1011 for transaction logacceleration while using a standard library, file system I/O, or otherinterface.

In a further embodiment, the acceleration module 150 may filter and/orintercept transaction log entries from a client 116. For example, atleast a portion of the acceleration module 150 may execute on the hostcomputing device 110, as a filter driver, as a layer in a storage stack,as part of the SML 130 or a device driver for the non-volatile storagedevice 102 and/or the non-volatile storage device 121, as part of amemory system 1018, or the like, and may be configured to receiverequests to store transaction log entries from one or more storageclients 116, such as a database system 116 a. In other embodiments, astorage client 116, such as a database system 116 a, may be aware of andconfigured to use the acceleration module 150 and/or the non-volatilestorage device 102, and may send requests to store transaction logentries to the acceleration module 150 directly.

FIG. 2 is a block diagram of a system 1100 comprising one embodiment ofan acceleration module 150 and an auto-commit memory (ACM) 1011. In oneembodiment, an auto-commit memory 1011 comprises a low-latency, highreliability memory medium, which may be exposed to the accelerationmodule 150 and/or other ACM users 116 for direct memory semantic access,at a memory semantic access and address granularity level of at leastbyte level, combined with logic and components together configured torestore the same state of data stored in the ACM memory buffer 1013 thatexisted prior to a restart event or other trigger and the same level ofmemory semantic access to data stored in the auto-commit memory 1011after the restart event or other trigger. In certain embodiments, theACM 1011 guarantees that data stored in the ACM 1011 will be accessibleafter a restart event or other trigger. The ACM 1011, in one embodiment,comprises a volatile memory medium 1013 coupled to a controller 104,logic, and other components that commit data to a non-volatile storagemedium 122 when necessary or when directed by an ACM user 116. In afurther embodiment, the ACM 1011 may include a natively non-volatilestorage medium such as phase change memory (PCM or PRAM), and atriggered commit action may process data on the non-volatile storagemedium 122 in response to a restart event such that the data remainsavailable to an owner 116 of the data after the restart event.

Accordingly, when data is written to the ACM 1011, it may not initiallybe “committed” per se (e.g., is not necessarily stored on a persistentmemory medium 122 and/or state); rather, a pre-configured process may besetup to preserve the ACM data and its state, if a restart event orother trigger occurs while the ACM data is stored in the ACM 1011. Thepre-configuring of this restart survival process is referred to hereinas “arming.” The ACM 1011 may be capable of performing thepre-configured commit action autonomously and with a high degree ofassurance, despite the system 1100 experiencing failure conditions,another restart event, and/or another trigger. As such, an entity 116that stores data on the ACM 1011 may consider the data to be“instantaneously committed” or safe from loss or corruption, at least assafe as if the data were stored in a non-volatile storage device such asa hard disk drive, tape storage medium, or the like.

In embodiments where the ACM 1011 comprises a volatile memory medium1013, the ACM 1011 may make the volatile memory medium 1013 appear as anon-volatile memory and/or non-volatile storage, may present thevolatile memory 1013 as a non-volatile medium, or the like, because theACM 1011 preserves data, such as ACM data and/or ACM metadata 1015,across system restart events or other triggers. The ACM 1011 may allow avolatile memory medium 1013 to be used as a non-volatile memory mediumby determining that a trigger event, such as a restart or failurecondition, has occurred, copying the contents of the volatile memorymedium 1013 to a non-volatile storage medium 122 during a hold-up timeafter the trigger event, and copying the contents back into the volatilememory medium 1013 from the non-volatile storage medium 122 after thetrigger event is over, power has been restored, the restart event hascompleted, or the like.

In one embodiment, the ACM 1011 is at least byte addressable. Anon-volatile memory medium 122 of the ACM 1011, in certain embodiments,may be natively byte addressable, directly providing the ACM 1011 withbyte addressability. In another embodiment, a non-volatile memory medium122 of the ACM 1011 is not natively byte addressable, but a volatilememory medium 1013 of the ACM 1011 is natively byte addressable, and theACM 1011 writes or commits the contents of the byte addressable volatilememory medium 1013 to the non-byte addressable non-volatile memorymedium 122 of the ACM 1011 in response to a trigger event, so that thevolatile memory medium 1013 renders the ACM 1011 byte addressable.

The ACM 1011 may be accessible to one or more computing devices, such asthe host 110. As used herein a computing device (e.g., the host 110)refers to a computing device capable of accessing an ACM 1011. The ACM1011 may be in communication with the host 110 over a data network 115;the host 110 may be a computing device that houses the ACM 1011 as aperipheral; the ACM 1011 may be attached to a system bus of the host110; and/or the ACM 1011 may otherwise be in communication with the host110. The host 110, in certain embodiments, may access the ACM 1011hosted by another computing device. The access may be implemented usingany suitable communication mechanism, including, but not limited to:RDMA, Infiniband, CPU programmed IO (CPIO), port-mapped IO (PMIO),memory-mapped IO (MMIO), a Block interface, a PCI-e bus, or the like.The host 110 may comprise one or more ACM users 116. As used herein, anACM user 116 refers to an entity (e.g., hardware and/or software)configured to access the ACM 1011, directly or indirectly, such as ahost computing device 110, a database system 116 a, operating system(OS), virtual operating platform (e.g., an OS with a hypervisor), aguest OS, application, process, thread, entity, utility, user, oranother storage client 116.

One or more ACM buffers 1013, in certain embodiments, may be mapped intoan address range of a physical memory address space addressable by a CPU111, a kernel, or the like of the host device 110, such as the memorysystem 1018 described below, over the network 115, over a bus (e.g., aPCI bus), or the like. For example, one or more ACM buffers 1013 may bemapped as directly attached physical memory, as MMIO addressablephysical memory over a PCI-e bus, or otherwise mapped as one or morepages of physical memory. At least a portion of the physically mappedACM buffers 1013, in a further embodiment, may be mapped into a virtualmemory address space, accessible to user-space processes or the like asvirtual memory.

Allowing ACM users 116 to directly address the ACM buffers 1013, incertain embodiments, bypasses one or more layers of the traditionaloperating system memory stack of the host device 110, providing directload/store operation access to kernel-space and/or user-spaceapplications. An operating system, using a kernel module, an applicationprogramming interface, the storage management layer (SML) 130 describedbelow, or the like, in one embodiment, maps and unmaps ACM buffers 1013to and from the memory system 1018 for one or more ACM users 116, andthe ACM users 116 may directly access an ACM buffer 1013 once theoperating system maps the ACM buffer 1013 into the memory system 1018.In a further embodiment, the operating system may also service systemflush calls for the ACM buffers 1013, or the like.

The storage management layer 130 and/or the SML API 132 described below,in certain embodiments, provide an interface for ACM users 116, anoperating system 116, a database system 116 a, and/or other entities torequest certain ACM functions, such as a map function, an unmapfunction, a flush function, and/or other ACM functions. To perform aflush operation in response to a flush request, the ACM 1011 may performa commit action for each ACM buffer 1013 associated with the flushrequest. Each ACM buffer 1013 is committed as indicated by the ACMmetadata 1015 of the associated ACM buffer 1013. A flush function, invarious embodiments, may be specific to one or more ACM buffers 1013,system-wide for all ACM buffers 1013, or the like. In one embodiment, aCPU 111, an operating system, or the like for the host 110 may requestan ACM flush operation in response to, or as part of a CPU cache flush,a system-wide data flush for the host 110, or another general flushoperation.

An ACM user 116, an operating system, or the like may request a flushoperation to maintain data consistency prior to performing a maintenanceoperation, such as a data snapshot or a backup, to commit ACM data priorto reallocating an ACM buffer 1013, to prepare for a scheduled restartevent, or for other circumstances where flushing data from an ACM buffer1013 may be beneficial. An ACM user 116, an operating system, or thelike, in certain embodiments, may request that the ACM 1011 map and/orunmap one or more ACM buffers 1013 to perform memory management for theACM buffers 1013; to reallocate the ACM buffers 1013 betweenapplications or processes; to allocate ACM buffers 1013 for new data,applications, or processes; to transfer use of the ACM buffers 1013 to adifferent host 110 (in shared ACM 1011 embodiments); or to otherwisemanipulate the memory mapping of the ACM buffers 1013. In anotherembodiment, the storage management layer 130 may dynamically allocate,map, and/or unmap ACM buffers 1013 using a resource management agent asdescribed below.

Since the ACM 1011, in certain embodiments, may be guaranteed toauto-commit the data stored thereon in the event of a trigger event, thehost 110, ACM user 116, or the like may view data written to the ACM1011 as being instantaneously “committed” or non-volatile, as the host110 or ACM user 116 may access the data both before and after thetrigger event. While a restart event, in one embodiment, may cause anACM user 116 such as a database system 116 a to be re-started orre-initialized, the data stored in the ACM 1011 may be in the samestate/condition after the restart event as it was before the restartevent. The host 110 may, therefore, write to the ACM 1011 using memorywrite semantics (and/or at CPU speeds and granularity), without the needfor explicit commit commands by relying on the pre-configured trigger ofthe ACM 1011 to commit the data in the event of a restart or othertrigger event.

The ACM 1011 may comprise a plurality of auto-commit buffers 1013, eachcomprising respective ACM metadata 1015. As discussed below, the ACMmetadata 1015 may include data to facilitate committing of ACM data inresponse to a triggering event for the auto-commit buffer 1013, such asa logical identifier for data in the ACM buffer 1013, an identifier of acommit agent 1020, instructions for a commit process or other processingprocedure, security data, or the like. The auto-commit buffers 1013 maybe of any suitable size, from a single sector, page, byte, or the like,to a virtual or logical page size (e.g., 80 to 400 kb). The size of theauto-commit buffers 1013 may be adapted according to the storagecapacity of the underlying non-volatile storage medium 122, and orhold-up time available from the secondary power supply 124.

In one embodiment, the ACM 1011 may advertise or present to the host110, to ACM users 116, or the like, a storage capacity of the ACMbuffers 1013 that is larger than an actual storage capacity of memory ofthe ACM buffers 1013. To provide the larger storage capacity, the ACM1011 may dynamically map and unmap ACM buffers 1013 to the memory system1018 and to the non-volatile backing memory 122 of the ACM 1011. Forexample, the ACM 1011 may provide virtual address ranges for the ACMbuffers 1013, and demand page data and/or ACM buffers 1013 to thenon-volatile storage medium 122 as ACM buffer 1013 accesses necessitate.In another embodiment, for ACM buffers 1013 that are armed to commit toone or more predefined LBAs of the non-volatile storage medium 122, theACM 1011 may dynamically move the ACM data and ACM metadata 1015 fromthe ACM buffers 1013 to the associated LBAs of the non-volatile storagemedium 122, freeing storage capacity of the ACM buffers 1013 to providea larger storage capacity. The ACM 1011 may further return the ACM dataand ACM metadata 1015 back to one or more ACM buffers 1013 as ACMbuffers become available, certain addresses outside the data ofcurrently loaded ACM buffers 1013 are requested, or the like, managingstorage capacity of the ACM buffers 1013.

The ACM 1011 may be pre-configured or “armed” to implement one or more“triggered commit actions” in response to a restart condition, or other,pre-determined condition or trigger. As used herein, a restart conditionor event may include, but is not limited to a software or hardwareshutdown/restart of a host 110, a failure in a host 110 computingdevice, a failure of a component of the host 110 (e.g., failure of thenetwork or a bus), a software fault (e.g., an fault in software runningon the host 110 or other computing device), a loss of the primary powerconnection 136, an invalid shutdown, power from the primary powerconnection 136 failing to satisfy a threshold, or another event that maycause the loss of data stored in a volatile memory 1013.

In one embodiment, a restart event comprises the act of the host 110commencing processing after an event that may cause the loss of datastored within a volatile memory of the host 110 or a component in thehost 110. The host 110 may commence/resume processing once the restartcondition or event has finished, a primary power source 136 isavailable, and the like.

The ACM 1011 may be configured to detect that a restart event/conditionor other trigger has occurred and/or respond to a restart event or othertrigger by initiating a recovery stage. During a recovery stage, the ACM1011 may restore the data of the ACM 1011 to the state prior to therestart event or other trigger. Alternatively, or in addition, duringthe recovery stage, the ACM 1011 may complete processing of ACM data orACM metadata 1015 needed to satisfy a guarantee that data in the ACM1011 is available to ACM users 116 after the restart event or othertrigger. Alternatively, or in addition, during the recovery stage, theACM 1011 may complete processing of ACM data or ACM metadata 1015 neededto satisfy a guarantee that data in the ACM 1011 is committed after therestart event. As used herein, “commit” may mean that data in the ACM1011 is protected from loss or corruption even after the restart eventor other trigger and is persisted as required per the arming informationassociated with the data. In certain embodiments, the recovery stageincludes processing ACM data and ACM metadata 1015 such that the ACMdata is persisted, even though a restart event or other triggeroccurred.

As used herein, a triggered commit action is a pre-configured commitaction that is armed to be performed by the ACM 1011 in response to atriggering event (e.g., a restart event, a flush command, or otherpre-determined event or trigger). In certain embodiments, the triggeredcommit action persists at least enough ACM data and/or ACM metadata 1015to make data of the ACM 1011 available after a system restart, tosatisfy a guarantee of the ACM 1011 that the data will be accessible toan ACM user 116 after a restart event, or other trigger. In certainembodiments, this guarantee is satisfied, at least in part, bycommitting and/or persisting data of the ACM 1011 to non-volatilestorage medium 122. A triggered commit action may be completed before,during, and/or after a restart event or other trigger. For example, theACM 1011 may write ACM data and ACM metadata 1015 to a predefinedtemporary location in the non-volatile storage medium 122 during ahold-up time after a restart event, and may copy the ACM data back intothe ACM buffers 1013, to an intended location in the non-volatilestorage medium 122, or perform other processing once the restart eventis complete.

A triggered commit action may be “armed” when the ACM 1011 is requestedand/or a particular ACM buffer 1013 is allocated for use by a host 110.In some embodiments, an ACM 1011 may be configured to implement atriggered commit action in response to other, non-restart conditions.For example, an operation directed to a particular logical address(e.g., a poke), may trigger the ACM 1011, a flush operation may triggerthe ACM 1011, or the like. This type of triggering may be used to committhe data of the ACM 1011 during normal operation (e.g., non-restart ornon-failure conditions).

The arming may occur when an auto-commit buffer 1013 is mapped into thememory system 1018 of the host 110. Alternatively, arming may occur as aseparate operation. As used herein, arming an auto-commit buffer 1013comprises performing the necessary configuration steps needed tocomplete the triggered action when the action is triggered. Arming mayinclude, for example, providing the ACM metadata 1015 to the ACM 1011 orthe like. In certain embodiments, arming further includes performing thenecessary configuration steps needed to complete a minimal set of stepsfor the triggered action, such that the triggered action is capable ofcompleting after a trigger event. In certain embodiments, arming furtherincludes verifying the arming data (e.g., verifying that the contents ofthe auto-commit buffer 1013, or portion thereof, can be committed asspecified in the ACM metadata 1015) and verifying that the ACM 1011 iscapable and configured to properly perform the triggered action withouterror or interruption.

The verification may ensure that once armed, the ACM 1011 can implementthe triggered commit action when required. If the ACM metadata 1015cannot be verified (e.g., the logical identifier or other ACM metadata1015 is invalid, corrupt, unavailable, or the like), the armingoperation may fail; memory semantic operations on the auto-commit buffer1013 may not be allowed unit the auto-commit buffer 1013 is successfullyarmed with valid ACM metadata 1015. For example, an auto-commit buffer1013 that is backed by a hard disk having a one-to-one mapping betweenLBA and physical address, may fail to arm if the LBA provided for thearming operation does not map to a valid (and operational) physicaladdress on the disk. Verification in this case may comprise querying thedisk to determine whether the LBA has a valid, corresponding physicaladdress and/or using the physical address as the ACM metadata 1015 ofthe auto-commit buffer 1013.

The armed triggered commit actions may be implemented in response to theACM 1011 (or other entity) detecting and/or receiving notification of atriggering event, such as a restart condition. In some embodiments, anarmed commit action is a commit action that can be performed by the ACM1011, and that requires little or no further communication with the host110 or other devices external to the “isolation zone” of the ACM 1011(discussed below). Accordingly, the ACM 1011 may be configured toimplement triggered commit actions autonomously of the host 110 and/orother components thereof. The ACM 1011 may guarantee that triggeredcommit actions can be committed without errors and/or despite externalerror conditions. Accordingly, in some embodiments, the triggered commitactions of the ACM 1011 do not comprise and/or require potentiallyerror-introducing logic, computations, and/or calculations. In someembodiments, a triggered commit action comprises committing data storedon the volatile ACM 1011 to a persistent storage location. In otherembodiments, a triggered commit action may comprise additionalprocessing of committed data, before, during, and/or after a triggeringevent, as described below. The ACM 1011 may implement pre-configuredtriggered commit actions autonomously; the ACM 1011 may be capable ofimplementing triggered commit actions despite failure or restartconditions in the host 110, loss of primary power, or another trigger.The ACM 1011 may implement triggered commit actions independently due toarming the ACM 1011 as described above.

The ACM metadata 1015 for an ACM buffer 1013, in certain embodiments,identifies the data of the ACM buffer 1013. For example, the ACMmetadata 1015 may identify an owner 116 of the data, may describe thedata itself, or the like. In one embodiment, an ACM buffer 1013 may havemultiple levels of ACM metadata 1015, for processing by multipleentities or the like. The ACM metadata 1015 may include multiple nestedheaders that may be unpackaged upon restart, and used by variousentities or commit agents 1020 to determine how to process theassociated ACM data to fulfill the triggered commit action as describedabove. For example, the ACM metadata 1015 may include block metadata,file metadata, application level metadata (e.g., database system 116 ametadata), process execution point or callback metadata, and/or otherlevels of metadata. Each level of metadata may be associated with adifferent commit agent 1020, or the like. In certain embodiments, theACM metadata 1015 may include security data, such as a signature for anowner of the associated ACM data, a pre-shared key, a nonce, or thelike, which the ACM 1011 may use during recovery to verify that a commitagent 1020, an ACM user 116, or the like is authorized to accesscommitted ACM metadata 1015 and/or associated ACM data. In this manner,the ACM 1011 may prevent ownership spoofing or other unauthorizedaccess. In one embodiment, the ACM 1011 does not release ACM metadata1015 and/or associated ACM data until a requesting commit agent 1020,ACM user 116, or the like provides valid authentication, such as amatching signature or the like.

One or more commit agents 1020, in certain embodiments, process ACM data(e.g., transaction log entries) based on the associated ACM metadata1015 to execute a triggered commit action. A commit agent 1020, invarious embodiments, may comprise software, such as a device driver, akernel module, the storage management layer 130, a thread, a user spaceapplication, or the like, and/or hardware, such as the controller 104. Acommit agent may be configured to interpret ACM metadata 1015 and toprocess the associated ACM data (e.g., transaction log entries)according to the ACM metadata 1015. In embodiments with multiple commitagents 1020, the ACM metadata 1015 may identify one or more commitagents 1020 to process the associated ACM data (e.g., transaction logentries). The ACM metadata 1015 may identify a commit agent 1020, invarious embodiments, by identifying a program/function of the commitagent 1020 to invoke (e.g., a file path of the program), by includingcomputer executable code of the commit agent 1020 (e.g., binary code orscripts), by including a unique identifier indicating which of a set ofregistered commit agents 1020 to use, and/or by otherwise indicating acommit agent 1020 associated with committed ACM metadata 1015. The ACMmetadata 1015, in certain embodiments, may be a functor or envelopewhich contains the information, such as function pointer and boundparameters for a commit agent 1020, to commit the ACM data (e.g.,transaction log entries) upon restart recovery.

In one embodiment, a primary commit agent 1020 processes ACM metadata1015, and hands-off or transfers ACM metadata 1015 and/or ACM data(e.g., transaction log entries) to one or more secondary commit agents1020 identified by the ACM metadata 1015. A primary commit agent 1020,in one embodiment, may be integrated with the ACM 1011, the controller104, or the like. An ACM user 116 or other third party, in certainembodiments, may provide a secondary commit agent 1020 for ACM data(e.g., transaction log entries) that the ACM user 116 or other thirdparty owns, and the primary commit agent 1020 may cooperate with theprovided secondary commit agent 1020 to process the ACM data. The one ormore commit agents 1020 for ACM data (e.g., transaction log entries), inone embodiment, ensure and/or guarantee that the ACM data (e.g.,transaction log entries) remains accessible to an owner 116 of the ACMdata (e.g., transaction log entries) after a restart event. As describedabove with regard to triggered commit actions, a commit agent 1020 mayprocess ACM metadata 1015 and associated ACM data (e.g., transaction logentries) to perform one or more triggered commit actions before, during,and/or after a trigger event, such as a failure or other restart event.

In one embodiment, a commit agent 1020, in cooperation with the ACM 1011or the like, may store the ACM metadata 1015 in a persistent ornon-volatile location (e.g., the non-volatile memory medium 122) inresponse to a restart or other trigger event. The commit agent 1020 maystore the ACM metadata 1015 at a known location, may store pointers tothe ACM metadata 1015 at a known location, may provide the ACM metadata1015 to an external agent or data store, or the like so that the commitagent 1020 may process the ACM metadata 1015 and associated ACM data(e.g., transaction log entries) once the restart event or other triggerhas completed. The known location may include one or more predefinedlogical block addresses or physical addresses of the non-volatilestorage medium 122, a predefined file, or the like. In certainembodiments, hardware of the ACM 1011 is configured to cooperate towrite the ACM metadata 1015 and/or pointers to the ACM metadata 1015 ata known location. In one embodiment, the known location may be atemporary location that stores the ACM data (e.g., transaction logentries) and ACM metadata 1015 until the host 110 has recovered from arestart event and the commit agent 1020 may continue to process the ACMdata (e.g., transaction log entries) and ACM metadata 1015. In anotherembodiment, the location may be a persistent location associated withthe ACM metadata 1015.

In response to completion of a restart event or other trigger, duringrecovery, in one embodiment, a commit agent 1020 may locate and retrievethe ACM metadata 1015 from the non-volatile storage medium 122, from apredefined location or the like. The commit agent 1020, in response tolocating and retrieving the ACM metadata 1015, locates the ACM data(e.g., transaction log entries) associated with the retrieved ACMmetadata 1015. The commit agent 1020, in certain embodiments, may locatethe ACM data (e.g., transaction log entries) in a substantially similarmanner as the commit agent 1020 locates the ACM metadata 1015,retrieving ACM data from a predefined location, retrieving pointers tothe ACM data from a predefined location, receiving the ACM data from anexternal agent or data store, or the like. In one embodiment, the ACMmetadata 1015 identifies the associated ACM data (e.g., transaction logentries) and the commit agent 1020 uses the ACM metadata 1015 to locateand retrieve the associated ACM data. For example, the commit agent 1020may use a predefined mapping to associate ACM data with ACM metadata1015 (e.g., the Nth piece of ACM data may be associated with the Nthpiece of ACM metadata 1015 or the like), the ACM metadata 1015 mayinclude a pointer or index for the associated ACM data, or anotherpredefined relationship may exist between committed ACM metadata 1015and associated ACM data. In another embodiment, an external agent mayindicate to the commit agent 1020 where associated ACM data (e.g.,transaction log entries) is located.

In response to locating and retrieving the ACM metadata 1015 andassociated ACM data (e.g., transaction log entries), the commit agent1020 may interpret the ACM metadata 1015 and process the associated ACMdata based on the ACM metadata 1015. For example, in one embodiment, theACM metadata 1015 may identify a block storage volume and LBA(s) wherethe commit agent 1020 is to write the ACM data (e.g., transaction logentries) upon recovery. In another embodiment, the ACM metadata 1015 mayidentify an offset within a file within a file system where the commitagent 1020 is to write the ACM data (e.g., transaction log entries) uponrecovery. In a further embodiment, the ACM metadata 1015 may identify anapplication specific persistent object where the commit agent 1020 is toplace the ACM data (e.g., transaction log entries) upon recovery, suchas a database record or the like. The ACM metadata 1015, in anadditional embodiment, may indicate a procedure for the commit agent1020 to call to process the ACM data (e.g., transaction log entries),such as a delayed procedure call or the like. In an embodiment where theACM 1011 advertises or presents volatile ACM buffers 1013 asnon-volatile storage, the ACM metadata 1013 may identify an ACM buffer1013 where the commit agent 1020 is to write the ACM data (e.g.,transaction log entries) upon recovery.

In certain embodiments, the ACM metadata 1015 may identify one or moresecondary commit agents 1020 to further process the ACM metadata 1015and/or associated ACM data (e.g., transaction log entries). A secondarycommit agent 1020 may process ACM metadata 1015 and associated ACM data(e.g., transaction log entries) in a substantially similar manner to thecommit agent 1020 described above. Each commit agent 1020 may processACM data (e.g., transaction log entries) in accordance with a differentlevel or subset of the ACM metadata 1015, or the like. The ACM metadata1015 may identify a secondary commit agent 1020, in various embodiments,by identifying a program/function of the secondary commit agent 1020 toinvoke (e.g., a file path of the program), by including computerexecutable code of the secondary commit agent 1020, by including aunique identifier indicating which of a set of registered secondarycommit agents 1020 to use, and/or by otherwise indicating a secondarycommit agent 1020 associated with committed ACM metadata 1015.

In one embodiment, a secondary commit agent 1020 processes a remainingportion of the ACM metadata 1015 and/or of the ACM data (e.g.,transaction log entries) after a previous commit agent 1020 hasprocessed the ACM metadata 1015 and/or the ACM data. In a furtherembodiment, the ACM metadata 1015 may identify another non-volatilemedium separate from the ACM 1011 for the secondary commit agent 1020 topersist the ACM data (e.g., transaction log entries) even after a hostexperiences a restart event. By committing the ACM metadata 1015 and theassociated ACM data (e.g., transaction log entries) from the ACM buffers1013 in response to a trigger event, such as a failure or other restartcondition, and processing the ACM metadata 1015 and the associated ACMdata once the trigger event has completed or recovered, the ACM 1011 mayguarantee persistence of the ACM data and/or performance of thetriggered commit action(s) defined by the ACM metadata 1015.

The ACM 1011 is communicatively coupled to a host 110 (e.g., over thenetwork 115, over a bus, or the like), which, like the host computingdevice 110 described above, may comprise one or more database systems116 a, operating systems 116, virtual machines 116, applications 116, aprocessor complex 111, a central processing unit 111 (CPU), and thelike. In the FIG. 2 example, these entities are referred to generally asACM users 116. Accordingly, as used herein, an ACM user 116 may refer toa database system, an operating system, a virtual machine operatingsystem (e.g., hypervisor), an application, a library, a CPUfetch-execute algorithm, or other program or process.

A database system 116 a, as described above, may comprise softwareand/or hardware configured to store and/or provide organized access todata. A database system 116 a may allow other clients 116 or users 116to define, create, query, update, and/or administer databases, tables,or other collections of data, using a query language, a graphical userinterface (GUI), a command line interface (CLI), or the like. A databasesystem 116 a may organize data according to one or more models, such asa relational model, a hierarchical model, an object model, a documentmodel, an entity-relationship model, an entity-attribute-value model,and/or another model. As described above, a database system 116 a mayrecord certain transactions in a database log or other transaction logdata structure. Recording transactions in transaction log may allow astorage client 116 such as a database client 116 a to undo and/or redoone or more transactions, to recreate data (e.g., one or more volatiledata structures lost due to a restart event of other trigger), as abackup or redundant copy of data, to replay and apply transactions on acopy of data in another location, or the like.

The ACM 1011 may be communicatively coupled to the host 110 (as well asthe ACM users 116) via a network 115, a bus, such as a system bus, aprocessor's memory exchange bus, or the like (e.g., HyperTransport,QuickPath Interconnect (QPI), PCI bus, PCI-e bus, or the like). In someembodiments, a bus comprises the primary power connection 136 (e.g., thenon-volatile storage device 102 may be powered over a communicationbus).

The ACM 1011 may be tightly coupled to the device used to perform thetriggered commit actions (e.g., the non-volatile storage device 102).For example, the ACM 1011 may be implemented on the same device,peripheral, card, or within the same “isolation zone” as the controller104 and/or secondary power source 124. The tight coupling of the ACM1011 to the components used to implement the triggered commit actionsdefines an “isolation zone,” which may provide an acceptable level ofassurance (e.g., based on industry standards and/or another metric) thatthe ACM 1011 is capable of implementing the triggered auto-commitactions in the event of a restart condition or other trigger. In theFIG. 2 example, the isolation zone of the ACM 1011 is provided by thetight coupling of the ACM 1011 with the autonomous controller 104 andsecondary power supply 124.

The controller 104 may comprise an I/O controller, such as a networkcontroller (e.g., a network interface controller), storage controller,dedicated restart condition controller or ACM controller, or the like.The controller 104 may comprise firmware, hardware, a combination offirmware and hardware, or the like. In the FIG. 2 example, thecontroller 104 comprises a storage controller, such as the storagecontroller 104 and/or non-volatile storage device controller describedabove. The controller 104 may be configured to operate independently ofthe host 110. As such, the controller 104 may be used to implement thetriggered commit action(s) of the ACM 1011 despite the restartconditions discussed above, such as failures in the host 110 (and/or ACMusers 116) and/or loss of the primary power connection 136.

The ACM 1011, in the depicted embodiment, is powered by a primary powerconnection 136, which may be provided by an external power supply, aninternal power supply unit (PSU), a system bus, the host 110, or thelike. In certain embodiments, the ACM 1011 also includes and/or iscoupled to a secondary power source 124. The secondary power source 124may power the ACM 1011 in the event of a failure to the primary powerconnection 136, and/or another trigger. The secondary power source 124may be capable of providing at least enough power to enable the ACM 1011and/or controller 104 to autonomously implement at least a portion of apre-configured triggered commit action(s) when the primary powerconnection 136 has failed, fallen below a threshold, or the like. TheACM 1011, in one embodiment, commits or persists at least enough data(e.g., ACM data and/or ACM metadata 1015) while receiving power from thesecondary power source 124, to allow access to the data once the primarypower connection 136 has been restored. In certain embodiments, asdescribed above, the ACM 1011 may perform at least a portion of thepre-configured triggered commit action(s) after the primary powerconnection 136 has been restored, using one or more commit agents 1020or the like.

The ACM 1011 may comprise one or more volatile memory buffers 1013. Inthe FIG. 2 example, the ACM 1011 includes one or more volatileauto-commit buffers 1013. The auto-commit buffers 1013 may beimplemented using a volatile Random Access Memory (RAM). In someembodiments, the auto-commit buffers 1013 may be embodied as independentcomponents of the ACM 1011 (e.g., in separate RAM modules).Alternatively, the auto-commit buffers 1013 may be implemented onembedded volatile memory (e.g., BRAM) available within the controller104, a processor complex 111, an FPGA, or other component of the ACM1011.

Each of the auto-commit buffers 1013 may be pre-configured (armed) witha respective triggered commit action. In some embodiments, eachauto-commit buffer 1013 may comprise its own, respective ACM metadata1015. The ACM metadata 1015, in some embodiments, identifies how and/orwhere the data stored on the auto-commit buffer 1013 is to be committed.In some examples, the ACM metadata 1015 may comprise a logicalidentifier (e.g., an object identifier, logical block address (LBA),file name, storage client 116 identifier, or the like) associated withthe data in the auto-commit buffer 1013. The logical identifier may bepredefined. In one embodiment, when an auto-commit buffer 1013 iscommitted, the data therein may be committed with the ACM metadata 1015(e.g., the data may be stored at a physical storage locationcorresponding to the logical identifier, in association with the logicalidentifier, with the logical identifier, or the like). To facilitatecommitting of ACM data (e.g., transaction log entries) during a hold-uptime after a restart event or other trigger, the ACM 1011 may write ACMdata and ACM metadata 1015 in a single atomic operation, such as asingle page write or the like. To permit writing of ACM and ACM metadata1015 in a single atomic operation, the ACM buffers 1013 may be sized tocorrespond to a single write unit for a non-volatile storage medium thatis used by the ACM 1011. In some embodiments, the ACM metadata 1015 maycomprise a network address, an LBA, or another identifier of a commitlocation for the data.

In a further embodiment, a logical identifier may associate data of anauto-commit buffer 1013 with an owner of the data, such as a databasesystem 116 or other storage client 116, so that the data and the ownermaintain the ownership relationship after a restart event. For example,the logical identifier may identify an application, an application type,a process ID, an ACM user 116, or another entity of a host device 110,so that the ACM data (e.g., transaction log entries) is persistentlyassociated with the identified entity. In one embodiment, a logicalidentifier may be a member of an existing namespace, such as a filesystem namespace, a user namespace, a process namespace, a logicaladdress space 134, or the like. In other embodiments, a logicalidentifier may be a member of a new or separate namespace, such as anACM namespace. For example, a globally unique identifier namespace, asmay be used in distributed systems for identifying communicatingentities, may be used as an ACM namespace for logical identifiers. TheACM 1011 may process committed ACM data (e.g., transaction log entries)according to a logical identifier for the data once a restart event hascompleted. For example, the ACM 1011 may commit the ACM data (e.g.,transaction log entries) to a logical identifier associated with atemporary location in response to a restart event or other trigger, andmay write the ACM data (e.g., transaction log entries) to a persistentlocation identified by another logical identifier during recovery afterthe restart event.

As described above, the ACM 1011 may be tightly coupled with thecomponents used to implement the triggered commit actions (e.g., the ACM1011 is implemented within an “isolation zone”), which ensures that thedata on the ACM 1011 will be committed in the event of a restartcondition. As used herein, a “tight coupling” refers to a configurationwherein the components used to implement the triggered commit actions ofthe ACM 1011 are within the same “isolation zone,” or two or moredistinct trusted “isolation zones,” and are configured to operatedespite external failure or restart conditions, such as the loss ofpower, invalid shutdown, host 110 failures, or the like. FIG. 2illustrates a tight coupling between the ACM 1011, the auto-commitbuffers 1013, the controller 104, which is configured to operateindependently of the host 110, and the secondary power source 124, whichis configured to power the controller 104 and the ACM 1011 (includingthe auto-commit buffers 1013) while the triggered commit actions arecompleted. Examples of a tight coupling include but are not limited toincluding the controller 104, the secondary power source 124, and theauto-commit buffers 1013 on a single printed circuit board (PCB), withina separate peripheral and/or appliance in electronic communication withthe host 110, or the like. In other embodiments, the ACM 1011 may betightly coupled to a different set of components (e.g., redundant hostdevices, redundant communication buses, redundant controllers,alternative power supplies, or the like).

The ACM 1011 may be accessible by the host 110 and/or ACM users 116running thereon. Access to the ACM 1011 may be provided using memoryaccess semantics, such as CPU load/store commands, DMA commands, 3rdparty DMA commands, RDMA commands, atomic test and set commands,manipulatable memory pointers, network requests, or the like. In someembodiments, memory semantic access to the ACM 1011 is implemented overthe network 115 (e.g., using RDMA and/or Infiniband), over a bus (e.g.,using a PCI-e BAR as described below), or the like.

In a memory semantic paradigm, ACM users 116 running on the host 110 mayaccess the ACM 1011 via a memory system 1018 of the host 110. The memorysystem 1018 may comprise a memory management unit, virtual memorysystem, virtual memory manager, virtual memory subsystem (or similarmemory address space) implemented by an operating system, avirtualization system (e.g., hypervisor), an application, or the like. Aportion of the ACM 1011 (e.g., one or more auto-commit buffers 1013) maybe mapped into the memory system 1018, such that memory semanticoperations implemented within the mapped memory address range (ACMaddress range 1021) are performed on the ACM 1011.

The storage management layer 130, in certain embodiments, allocatesand/or arbitrates the storage capacity of the ACM 1011 between multipleACM users 116, using a resource management agent or the like. Theresource management agent of the storage management layer 130 maycomprise a kernel module provided to an operating system of the hostdevice 110, a device driver, a thread, a user space application, or thelike. In one embodiment, the resource management agent determines howmuch storage capacity of the ACM buffers 1013 to allocate to an ACM user116 and how long the allocation is to last. Because, in certainembodiments, the ACM 1011 commits or persists data across restartevents, the resource management agent may allocate storage capacity ofACM buffers 1013 across restart events.

The resource management agent may assign different ACM buffers 1013 todifferent ACM users 116, such as different kernel and/or user spaceapplications. The resource management agent may allocate ACM buffers1013 to different usage types, may map ACM buffers 1013 to differentnon-volatile storage medium 122 locations for destaging, or the like. Inone embodiment, the resource management agent may allocate the ACMbuffers 1013 based on commit agents 1020 associated with the ACM buffers1013 by the ACM metadata 1015 or the like. For example, a master commitagent 1020 may maintain an allocation map in ACM metadata 1015identifying allocation information for ACM buffers 1013 of the ACM 1011and identifying, in one embodiment, one or more secondary commit agents1020, and the master commit agent 1020 may allocate a portion of the ACMbuffers 1013 to each of the secondary commit agents 1020. In anotherembodiment, commit agents 1020 may register with the resource managementagent, may request resources such as ACM buffers 1013 from the resourcemanagement agent, or the like. The resource management agent may use apredefined memory management policy, such as a memory pressure policy orthe like, to allocate and arbitrate ACM buffer 1013 storage capacitybetween ACM users 116.

In some embodiments, establishing an association between an ACM addressrange 1021 within the memory system 1018 and the ACM 1011 may comprisepre-configuring (arming) the corresponding auto-commit buffer(s) 1013with a triggered commit action. As described above, thispre-configuration may comprise associating the auto-commit buffer 1013with a logical identifier or other metadata, which may be stored in theACM metadata 1015 of the buffer 1013. As described above, the ACM 1011may be configured to commit the buffer data to the specified logicalidentifier in the event of a restart condition, or to perform otherprocessing in accordance with the ACM metadata 1015.

Memory semantic access to the ACM 1011 may be implemented using anysuitable address and/or device association mechanism. In someembodiments, memory semantic access is implemented by mapping one ormore auto-commit buffers 1013 of the ACM 1011 into the memory system1018 of the host 110. In some embodiments, this mapping may beimplemented over the network 115, using a bus, or the like. For example,a bus may comprise a PCI-e (or similar) communication bus, and themapping may comprise associating a Base Address Register (BAR) of anauto-commit buffer 1013 of the ACM 1011 on the bus with the ACM addressrange 1021 in the memory system 1018 (e.g., the host 110 mapping a BARinto the memory system 1018).

The association may be implemented by an ACM user 116 (e.g., by avirtual memory system of an operating system or the like), through anAPI of a storage layer, such as the storage management layer (SML) 130.The storage management layer 130 may be configured to provide access tothe auto-commit memory 1011 to ACM users 116. The storage managementlayer 130 may comprise a driver, kernel-level application, user-levelapplication, library, or the like. The storage management layer 130 mayprovide a SML API 132 comprising, inter alia, an API for mappingportions of the auto-commit memory 1011 into the memory system 1018 ofthe host 110, for unmapping portions of the auto-commit memory 1011 fromthe memory system 1018 of the host 110, for flushing the ACM buffers1013, for accessing and managing transaction log data structures usingthe acceleration module 150, or the like.

The storage management layer 130 may be configured to maintain metadata135, which may include a forward index 134 comprising associationsbetween logical identifiers of a logical address space and physicalstorage locations on the auto-commit memory 1011 and/or persistentstorage medium 122. In some embodiments, ACM 1011 may be associated withone or more virtual ranges that map to different address ranges of a BAR(or other addressing mechanism). The virtual ranges may be accessed(e.g., mapped) by different ACM users 116. Mapping or exposing a PCI-eACM BAR to the host memory 1018 may be enabled on demand by way of a SMLAPI 132 call.

The SML API 132 may comprise interfaces for mapping an auto-commitbuffer 1013 into the memory system 1018. In some embodiments, the SMLAPI 132 may extend existing memory management interfaces, such asmalloc, calloc, or the like, to map auto-commit buffers 1013 into thevirtual memory range of ACM user applications 116 (e.g., a malloc callthrough the SML API 132 may map one or more auto-commit buffers 1013into the memory system 1018). Alternatively, or in addition, the SML API132 may comprise one or more explicit auto-commit mapping functions,such as “ACM alloc,” “ACM_free,” or the like. Mapping an auto-commitbuffer 1013 may further comprise configuring a memory system 1018 of thehost to ensure that memory operations are implemented directly on theauto-commit buffer 1013 (e.g., prevent caching memory operations withina mapped ACM address range 1021).

The association between the ACM address range 1021 within the hostmemory system 1018 and the ACM 1011 may be such that memory semanticoperations performed within a mapped ACM address range 1021 areimplemented directly on the ACM 1011 (e.g., without intervening systemRAM, or other intermediate memory, in a typical write commit operation,additional layers of system calls, or the like). For example, a memorysemantic write operation implemented within the ACM address range 1021may cause data to be written to the ACM 1011 (e.g., on one or more ofthe auto-commit buffers 1013). Accordingly, in some embodiments, mappingthe ACM address range 1021 may comprise disabling caching of memoryoperations within the ACM address range 1021, such that memoryoperations are performed on an ACM 1011 and are not cached by the host(e.g., cached in a CPU cache, in host volatile memory, or the like).Disabling caching within the ACM address range 1021 may comprise settinga “non-cacheable” flag attribute associated with the ACM range 1021,when the ACM range 1021 is defined.

As discussed above, establishing an association between the host memorysystem 1018 and the ACM 1011 may comprise “arming” the ACM 1011 toimplement a pre-determined triggered commit action. The arming maycomprise providing the ACM 1011 with a logical identifier (e.g., alogical block address, a file name, a network address, a stripe ormirroring pattern, or the like). The ACM 1011 may use the logicalidentifier to arm the triggered commit action. For example, the ACM 1011may be triggered to commit data to a persistent storage medium using thelogical identifier (e.g., the data may be stored at a physical addresscorresponding to the logical identifier and/or the logical identifiermay be stored with the data in a log-based data structure). Arming theACM 1011 allows the host 110 to view subsequent operations performedwithin the ACM address range 1021 (and on the ACM 1011) as being“instantly committed,” enabling memory semantic write granularity (e.g.,byte level operations) and speed with instant commit semantics.

Memory semantic writes such as a “store” operation for a CPU aretypically synchronous operations such that the CPU completes theoperation before handling a subsequent operation. Accordingly, memorysemantic write operations performed in the ACM memory range 1021 can beviewed as “instantly committed,” obviating the need for a corresponding“commit” operation in the write-commit operation, which maysignificantly increase the performance of ACM users 116 affected bywrite-commit latency. The memory semantic operations performed withinthe ACM memory range 1021 may be synchronous. Accordingly, ACM 1011 maybe configured to prevent the memory semantic operations from blocking(e.g., waiting for an acknowledgement from other layers, such as thebus, or the like). Moreover, the association between ACM address range1021 and the ACM 1011 allow memory semantic operations to bypass systemcalls (e.g., separate write and commit commands and their correspondingsystem calls) that are typically included in write-commit operations.

Data transfer between the host 110 and the ACM 1011 may be implementedusing any suitable data transfer mechanism including, but not limitedto: the host 110 performing processor IO operations (PIO) with the ACM1011 via the bus; the ACM 1011 (or other device) providing one or moreDMA engines or agents (data movers) to transfer data between the host110 and the ACM 1011; the host 110 performing processor cachewrite/flush operations; or the like.

As discussed above, an ACM may be configured to automatically perform apre-configured triggered commit action in response to detecting certainconditions (e.g., restart or failure conditions, or another trigger). Insome embodiments, the triggered commit action may comprise committingdata stored on the ACM 110 to a persistent storage medium 122.Accordingly, in some embodiments, the ACM 1011 may comprise and/or be incommunication with a persistent storage medium 122.

The ACM 1011 may be integrated with and/or tightly coupled to thenon-volatile storage device 102 and/or the controller 104. Thecontroller 104, in the depicted embodiment, comprises a write datapipeline 106 and a read data pipeline 108. The non-volatile storagedevice 102 may be capable of persisting data on a non-volatile storagemedium 122, such as NAND flash or another solid-state storage medium.

The data on the ACM 1011 may be committed to the persistent storage 122in accordance with the ACM metadata 1015, such as a logical identifieror the like. The ACM 1011, in certain embodiments, may commit the datato a temporary location for further processing after a restart event,may commit the data to a final intended location, or the like as,described above. In embodiments where the non-volatile storage medium122 is a sequential storage device, committing the data may comprisestoring the logical identifier or other ACM metadata 1015 with thecontents of the auto-commit buffer 1013 (e.g., in a packet or containerheader), to an append point of a sequential, log-based writingstructure, or the like. In embodiments where the non-volatile storagemedium 122 comprises magnetic media (e.g., a hard disk drive) or thelike having a 1:1 mapping between logical identifier and physicaladdress, the contents of the auto-commit buffer 1013 may be committed tothe storage location to which the logical identifier maps. Since thelogical identifier or other ACM metadata 1015 associated with the datais pre-configured (e.g., armed), the ACM 1011 may implement a triggeredcommit action independently of the host 110. The secondary power supply124 may supply power to the volatile auto-commit buffers 1013 of the ACM1011 until the triggered commit actions are completed (e.g., confirmedto be completed), until the triggered commit actions are performed to apoint at which the ACM 1011 may complete the triggered commit actionsduring recovery after a restart event, or the like.

In some embodiments, the ACM 1011 commits data in a way that maintainsan association between the data and its corresponding logical identifier(per the ACM metadata 1015). In embodiments where the non-volatilestorage medium 122 comprises a hard disk, the data may be committed to astorage location corresponding to the logical identifier, which may beoutside of the isolation zone 1301 described below (e.g., using alogical identifier to physical address conversion). In other embodimentsin which the non-volatile storage medium 122 comprises a sequentialmedium, such as a solid-state storage medium, the data may be storedsequentially and/or in a log-based format as described above. Asequential storage operation may comprise storing the contents of anauto-commit buffer 1013 with a corresponding logical identifier (e.g.,as indicated by the ACM metadata 1015). In one embodiment, the data ofthe auto-commit buffer 1013 and the corresponding logical identifier arestored together on the medium 122 according to a predetermined pattern.In certain embodiments, the logical identifier is stored before thecontents of the auto-commit buffer 1013. The logical identifier may beincluded in a header of a packet comprising the data, or in anothersequential and/or log-based format. The association between the data andlogical identifier may allow a data index to be reconstructed, or thelike.

As described above, the auto-commit buffers 1013 of the ACM 1011 may bemapped into the memory system 1018 of the host 110, enabling the ACMusers 116 of access these buffers 1013 using memory access semantics. Insome embodiments, the mappings between logical identifiers andauto-commit buffers 1013 may leverage a virtual memory system of thehost 110.

For example, an address range within the memory system 1018 may beassociated with a “memory mapped file.” A memory mapped file maycomprise a virtual memory abstraction in which a file, portion of afile, or block device is mapped into the memory system 1018 addressspace for more efficient memory semantic operations on data of thenon-volatile storage device 102. An auto-commit buffer 1013 may bemapped into the host memory system 1018 as a memory mapped file or asimilar abstraction. The ACM memory range 1021 may, therefore, berepresented by a memory mapped file. The backing file may be stored onthe non-volatile storage medium 122 within the isolation zone 1301 (SeeFIG. 5 below) or another network attached non-volatile storage device102 also protected by an isolation zone 1301. The auto-commit buffers1013 may correspond to a file, a portion of a file (e.g., the fileitself may be very large, exceeding the capacity of the auto-commitbuffers 1013 and/or the non-volatile storage medium 122), or the like.

When a portion of a file is mapped to an auto-commit buffer 1013, theACM user 116 (or other entity) may identify a desired offset within thefile and the range of blocks in the file that will operate with ACMcharacteristics (e.g., have ACM semantics). This offset may have apredefined logical identifier and the logical identifier and range maybe used to trigger committing the auto-commit buffer(s) 1013 mappedwithin the file. Alternatively, a separate offset for a block (or rangeof blocks) into the file may serve as a trigger for committing theauto-commit buffer(s) 1013 mapped to the file. For example, a memoryoperation (e.g., load, store, poke, or the like) being performed on datain the separate offset or range of blocks may comprise a trigger eventthat causes the auto-commit buffer(s) 1013 mapped to the file to becommitted.

The underlying logical identifier may change, however (e.g., due tochanges to other portions of the file, file size changes, or the like).When a change occurs, the storage management layer 130 (e.g., via theSML API 132, an ACM user 116, the acceleration module 150, or otherentity) may update the ACM metadata 1015 of the correspondingauto-commit buffers 1013. In some embodiments, the storage managementlayer 130 may be configured to query the host 110 (e.g., database system116 a, operating system, hypervisor, or other application 116) forupdates to the logical identifier of files associated with auto-commitbuffers 1013. The queries may be initiated by the SML API 132 and/or maybe provided as a hook (e.g., callback mechanism) into the host 110. Whenthe ACM user 116 no longer needs the auto-commit buffer 1013, thestorage management layer 130 may de-allocate the buffer 1013 asdescribed above. De-allocation may further comprise informing the host110 that updates to the logical identifier are no longer needed, or thelike.

In some embodiments, a file may be mapped across multiple storagedevices (e.g., the storage devices may be formed into a RAID group, maycomprise a virtual storage device, or the like). Associations betweenauto-commit buffers 1013 and the file may be updated to reflect the filemapping. This may allow the auto-commit buffers 1013 to commit the datato the proper storage device. The ACM metadata 1015 of the auto-commitbuffers 1013 may be updated in response to changes to the underlyingfile mapping and/or partitioning as described above. Alternatively, thefile may be “locked” to a particular mapping or partition while theauto-commit buffers 1013 are in use. For example, if aremapping/repartitioning of a file is required, the correspondingauto-commit buffers 1013 may commit data to the file, and then bere-associated with the file under the new mapping/partitioning scheme.The SML API 132 may comprise interfaces and/or commands for using thestorage management layer 130 to lock a file, release a file, and/orupdate ACM metadata 1015 in accordance with changes to a file.

Committing the data to solid-state and/or non-volatile storage 122 maycomprise the storage controller 104 accessing data from the ACM 1011auto-commit buffers 1013, associating the data with the correspondinglogical identifier (e.g., labeling the data), and/or injecting thelabeled data into the write data pipeline 106. In some embodiments, toensure there is a page program command capable of persisting the ACMdata (e.g., transaction log entries), the storage controller 104maintains two or more pending page programs during operation. The ACMdata (e.g., transaction log entries) may be committed to thenon-volatile storage medium 122 before writing the power loss identifier(power-cut fill pattern) described above.

Although a single auto-commit memory 1011 is depicted, in otherembodiments, the system 1100 may comprise a plurality of auto-commitmemories 1011. In the FIG. 4 example, memory semantic accessesimplemented by the host 110 may be stored on a plurality of ACMs 1011.In some embodiments, host data may be mirrored between multiple ACMs1011. The mirroring may be implemented using a multi-cast bus,rebroadcasting data from a first ACM 1011 to a second ACM 1011, or thelike. The ACMs 1011 may be local to one another (e.g., on the same localbus), on different systems or hosts 110 in communication over thenetwork 115, or the like.

FIG. 3 is a block diagram 1300 of one embodiment of a commit agent 1020within an isolation zone 1301. The commit agent 1020 may be tightlycoupled (e.g., within an isolation zone 1301) to the auto-commit memory1011, the non-volatile storage controller 104, the non-volatile storagemedium 122, and/or the secondary power supply 124, one or more of whichmay be in communication with and/or may cooperate with the accelerationmodule 150 to provide transaction log acceleration. The tight couplingmay comprise implementing one or more of these components 1122, 1011,104, 122, and/or 124 on the same die, in the same peripheral device, onthe same card (e.g., the same PCB), on the same network appliance,within a pre-defined isolation zone 1301, or the like. The tightcoupling may ensure that the triggered commit actions of the ACM buffers1013 are committed in the event of a restart condition or other trigger.

The commit agent 1020, in the depicted embodiment, includes a monitormodule 122, which may be configured to detect restart conditions oranother trigger, such as power loss or the like, on the primary powerconnection 136 or the like. The monitor module 122 may be configured tosense or detect triggering events, such as restart conditions (e.g.,shutdown, restart, power failures, communication failures, host orapplication failures, a power level that fails to satisfy a threshold,or the like) and, in response, to cause the commit module 1320 toinitiate the commit loss mode of the commit agent 1020 (e.g., failureloss mode) and/or to trigger the operations of other modules, such asmodules 1312, 1314, 1316, 1317, and/or 1318. The commit module 1320, inthe depicted embodiment, includes an identification module 1312, aterminate module 1314, a corruption module 1316, and a completion module1318.

The identification module 1312 may be configured to identify triggeredcommit actions to be performed for each ACM buffer 1013 of the ACM 1011.The identification module 1312 may prioritize operations based onrelative importance, with acknowledged operations being given a higherpriority than non-acknowledged operations. The contents of auto-commitbuffers 1013 that are armed to be committed may be assigned a highpriority due to the “instant commit” semantics supported thereby. Insome embodiments, the ACM triggered commit actions may be given a higherpriority than the acknowledged contents of the write data pipeline 106.Alternatively, the contents of armed auto-commit buffers 1013 may beassigned the “next-highest” priority, or the like. The priorityassignment may be user configurable (e.g., via an API, IO control(IOCTL) command, GUI, CLI, or the like).

The termination module 1314 may terminate non-essential operations toallow “essential” to continue. The termination module 1314 may beconfigured to hold up portions of the ACM 1011 that are “armed” to becommitted (e.g., armed auto-commit buffers), and may terminate power tonon-armed (unused) portions of the auto-commit memory 1011. Thetermination module 1314 may be further configured to terminate power toportions of the ACM 1011 (e.g., individual auto-commit buffers 1013) asthe contents of those buffers are committed.

The corruption module 1316 may identify corrupt (or potentially corrupt)data in the write data pipeline 106. The corruption module 1316 may befurther configured to identify corrupt ACM data 1011 (e.g., data thatwas written to the ACM 1011 during a power disturbance or other restartcondition). The corruption module 1316 may be configured to preventcorrupt data on the ACM 1011 from being committed in a triggered commitaction.

An ACM module 1317 may be configured to access armed auto-commit buffersin the auto-commit memory 1011, identify the ACM metadata 1015associated therewith (e.g., label the data with the correspondinglogical identifier per the ACM metadata 1015), and inject the data(and/or metadata 1015) into the write data pipeline 106 of thenon-volatile storage controller 104. In some embodiments, the logicalidentifier (or other ACM metadata 1015) of the auto-commit buffer 1013may be stored in the buffer 1013 itself. In this case, the contents ofthe auto-commit buffer 1013 may be streamed directly into a sequentialand/or log-based storage device 102 without first identifying and/orlabeling the data. The ACM module 1317 may inject data before or afterdata currently in the write data pipeline 106. In some embodiments, datacommitted from the ACM 1011 is used to “fill out” the remainder of awrite buffer of the write data pipeline 106 (e.g., after removingpotentially corrupt data). If the remaining capacity of the write bufferis insufficient, the write buffer may be written to the non-volatilestorage 122, and a next write buffer may be filled with the remainingACM data.

As discussed above, in some embodiments, the non-volatile storagecontroller 104 may maintain an armed write operation (e.g., logical pagewrite) to store the contents of the write data pipeline 106 in the eventof power loss or another trigger. When used with an ACM 1011, two (ormore) armed write operations (logical page writes) may be maintained toensure the contents of both the write data pipeline 106, and all thearmed buffers 1013 of the ACM 1011 can be committed in the event of arestart condition or another trigger. Because a logical page in a writebuffer may be partially filled when a trigger event occurs, the writebuffer may be sized to hold at least one more logical page of data thanthe total of all the data stored in all ACM buffers 1013 of the ACM 1011and the capacity of data in the write data pipeline 106 that has beenacknowledged as persisted. In this manner, there may be sufficientcapacity in the write buffer to complete the persistence of the ACM 1011in response to a trigger event. Accordingly, the auto-commit buffers1013 may be sized according to the amount of data the ACM 1011 iscapable of committing. Once this threshold is met, in certainembodiments, the storage management layer 130 may reject requests to useACM buffers 1013 until more becomes available, may destage or otherwisemove data from the ACM buffers 1013 to the non-volatile storage medium122, or the like.

The completion module 1318 may be configured to flush the write datapipeline 106 regardless of whether the certain buffers, packets, and/orpages are completely filled. The completion module 1318 may beconfigured to perform the flush (e.g., and insert the related paddingdata) after data on the ACM 1011 (if any) has been injected into thewrite data pipeline 106. The completion module 1318 may be furtherconfigured to inject completion indicator into the write data pipeline106, which may be used to indicate that a restart condition or othertrigger occurred (e.g., a restart condition fill pattern). This fillpattern may be included in the write data pipeline 106 after injectingthe triggered data from the ACM 1011, or the like.

As discussed above, the secondary power supply 124 may be configured toprovide sufficient power to store the contents of the ACM 1011 as wellas “in flight” or pending data in the write data pipeline 106. Storingthis data may comprise one or more write operations (e.g., page programoperations), in which data is persistently stored on the non-volatilestorage medium 122. In the event a write operation fails, another writeoperation, on a different storage location, may be attempted. Theattempts may continue until the data is successfully persisted on thenon-volatile storage medium 122. The secondary power supply 124 may beconfigured to provide sufficient power for each of a plurality of suchpage program operations to complete. Accordingly, in certainembodiments, the secondary power supply 124 may be configured to providesufficient power to complete double (or more) page program writeoperations as required to store the data of the ACM 1011 and/or writedata pipeline 106.

FIG. 4 is a block diagram 1500 depicting a host computing device 110with an acceleration module 150 accessing an ACM 1011 using memoryaccess semantics, providing transaction log acceleration in cooperationwith a file system module 1558 and/or a storage management layer 130(e.g., the storage management layer 130 described above). The hostcomputing device 110 may comprise a processor complex/CPU 111, which mayinclude, but is not limited to, one or more of a general purposeprocessor, an application-specific processor, a reconfigurable processor(e.g., FPGA), a processor core, a combination of processors, a processorcache, a processor cache hierarchy, or the like. In one embodiment, theprocessor complex 111 comprises a processor cache, and the processorcache may include one or more of a write combine buffer, an L1 processorcache, an L2 processor cache, an L3 processor cache, a processor cachehierarchy, and other types of processor cache. One or more ACM users 116(e.g., operating systems, database systems 116 a, applications, and soon) operate on the host 110.

The host 110 may be communicatively coupled to the ACM 1011 via thenetwork 115, via a bus (e.g., a PCI-e bus), or the like. Portions of theACM 1011 may be made accessible to the host 110 by mapping one or moreauto-commit buffers 1013 into the memory system 1018 of the host 110. Insome embodiments, mapping comprises associating an address range withinthe host memory system 1018 with an auto-commit buffer 1013 of the ACM1011. These associations may be enabled using the SML API 132 and/orstorage management layer 130 available on the host 110.

The storage management layer 130 may comprise libraries and/or provideinterfaces (e.g., SML API 132) to implement the memory access semanticsdescribed above. The API 132 may be used to access the ACM 1011 usingmemory access semantics via a memory semantic access module 1522. Othertypes of access, such as access to the non-volatile storage 122, to thenon-volatile storage device 121, or the like may be provided via a blockdevice interface 1520 or the like.

The storage management layer 130 may be configured to memory mapauto-commit buffers 1013 of the ACM 1011 into the memory system 1018(via the SML API 132). The memory map may use a virtual memoryabstraction of the memory system 1018. For example, a memory map may beimplemented using a memory mapped file abstraction. In this example, theoperating system (or application) 116 designates a file to be mappedinto the memory system 1018. The file is associated with a logicalidentifier (LID) 1025 (e.g., logical block address, storage client 116identifier), which may be maintained by a file system, an operatingsystem 116, the acceleration module 150, or the like.

The memory mapped file may be associated with an auto-commit buffer 1013of the ACM 1013. The association may be implemented by the storagemanagement layer 130 using the network 115, a bus, or the like. Thestorage management layer 130 may associate the address range of thememory mapped file (e.g., in the memory system 1018) with a deviceaddress of an auto-commit buffer 1013 on the ACM 1011. In the FIG. 4example, the ACM address range 1021 in the memory system 1018 isassociated with the auto-commit buffer 1013.

As discussed above, providing memory access semantics to the ACM 1011may comprise “arming” the ACM 1011 to commit data stored thereon in theevent of failure or other restart. The pre-configured arming ensuresthat, in the event of a restart, data stored on the ACM 1011 will becommitted to the proper logical identifier. The pre-configuration of thetrigger condition enables applications 116 to access the auto-commitbuffer 1013 using “instant-commit” memory access semantics. The logicalidentifier used to arm the auto-commit buffer may be obtained from anoperating system, the memory system 1018 (e.g., virtual memory system),a storage client 116 such as a database system 116 a, the accelerationmodule 150, or the like.

The storage management layer 130 may be configured to arm theauto-commit buffers 1013 with a logical identifier (e.g., automatically,by callback, and/or via the SML API 132). Each auto-commit buffer 1013may be armed to commit data to a different logical identifier (e.g.,different LBA, persistent identifier, or the like), which may allow theACM 1011 to provide memory semantic access to a number of different,concurrent ACM users 116. In some embodiments, arming an auto-commitbuffer 1013 comprises setting the ACM metadata 1015 with a logicalidentifier. In the FIG. 4 example, the ACM address range 1021 may beassociated with the logical identifier 1025, and the ACM metadata 1015of the associated auto-commit buffer may be armed with the correspondinglogical identifier 1025.

The storage management layer 130 may arm an auto-commit buffer using anI/O control (IOCTL) command comprising the ACM address range 1021, thelogical identifier 1025, and/or an indicator of which auto-commit buffer1013 is to be armed. The storage management layer 130 (e.g., through theSML API 132) may provide an interface to disarm or “detach” theauto-commit buffer 1013. The disarm command may cause the contents ofthe auto-commit buffer 1013 to be committed as described above (e.g.,committed to the non-volatile storage device 122). A detach may furthercomprise “disarming” the auto-commit buffer 1013 (e.g., clearing the ACMmetadata 1015). The storage management layer 130 may be configured totrack mappings between address ranges in the memory system 1018 andauto-commit buffers 1013 so that a detach command is performedautomatically.

Alternatively, or in addition, the storage management layer 130 may beintegrated into the operating system (and/or virtual operating system,e.g., hypervisor) of the host 110. This may allow the auto-commitbuffers 1013 to be used by a virtual memory demand paging system. Theoperating system may (through the SML API 132 or other integrationtechnique) map/arm auto-commit buffers for use by ACM users 116. Theoperating system may issue commit commands when requested by an ACM user116 and/or its internal demand paging system. Accordingly, the operatingsystem may use the ACM 1011 as another, generally available virtualmemory resource.

Once an ACM user 116, the acceleration module 150, or the like hasmapped the ACM address range 1021 to an auto-commit buffer 1013 and hasarmed the buffer 1013, the ACM user 116, the acceleration module 150, orthe like may access the resource using memory access semantics, and mayconsider the memory accesses to be “logically” committed as soon as thememory access has completed. The ACM user 116 may view the memorysemantic accesses to the ACM address range 1021 to be “instantlycommitted” because the ACM 1011 is configured to commit the contents ofthe auto-commit buffer (to the logical identifier 1025) regardless ofexperiencing restart conditions. Accordingly, the ACM user 116 may notbe required to perform separate write and commit commands (e.g., asingle memory semantic write is sufficient to implement a write-commit).Moreover, the mapping between the auto-commit buffer 1013 and the ACM1011 disclosed herein removes overhead due to function calls, systemcalls, and even a hypervisor (if the ACM user 116 is running in avirtual machine) that typically introduce latency into the write-commitpath. The write-commit latency time of the ACM user 116 may therefore bereduced to the time required to access the ACM 1011 itself.

The storage management layer 130 may be configured to provide a“consistency” mechanism for obtaining a consistent state of the ACM 1011(e.g., a barrier, snapshot, or logical copy). The consistency mechanismmay be implemented using metadata maintained by the storage managementlayer 130, which, as described above, may track the triggeredauto-commit buffers 1013 in the ACM 1011. A consistency mechanism maycomprise the storage management layer 130 committing the contents of alltriggered auto-commit buffers 1013, such that the state of thepersistent storage is maintained (e.g., store the contents of theauto-commit buffers 1013 on the non-volatile storage 122, or otherpersistent storage).

A DMA engine, RDMA engine, or the like may be used to perform bulkand/or low latency data transfers between an ACM user 116, theacceleration module 150, or the like and the ACM 1011. In someembodiments, the ACM 1011 may implement one or more DMA engines and/orRDMA engines, which may be allocated and/or accessed by ACM users 116and/or the acceleration module 150 using the storage management layer130 (e.g., through the SML API 132). The DMA engines may comprise localDMA transfer engines for transferring data on a local, system bus, RDMAtransfer engines for transferring data using the network 115, or thelike.

In some embodiments, the storage management layer 130 may compriselibraries and/or publish APIs adapted to a particular set of ACM users116. For example, the storage management layer 130 may provide orcooperate with the acceleration module 150, which may be adapted forapplications whose performance is tied to write-commit latency, such astransaction logs (e.g., a database system 116 a, file system, and/orother transaction log client 116), store and forward messaging systems,persistent object caching, storage device metadata, and the like. Theacceleration module 150 may provide an Instant Committed Log Library orthe like for a persistent transaction log, or another interface for adifferent transaction log data structure.

The acceleration module 150 may provide mechanisms for mappingauto-commit buffers 1013 of the ACM 1011 into the memory system 1018 ofan ACM user 116 as described above. ACM users 116 (or the accelerationmodule 150 itself) may implement an efficient “supplier/consumer”paradigm for auto-commit buffer 1013 allocation, arming, and access. Forexample, a “supplier” thread or process (e.g., in the application spaceof the ACM users 116) may be used to allocate and/or arm auto-commitbuffers 1013 for the ACM user 116 (e.g., map auto-commit buffers 1013 toaddress ranges within the memory system 1018 of the host 110, arm theauto-commit buffers 1013 with a logical identifier, and so on). A“consumer” thread or process of the ACM user 116 and/or the accelerationmodule 150 may then accesses the pre-allocated auto-commit buffers 1013.In this approach, allocation and/or arming steps may be taken out of thewrite-commit latency path of the consumer thread. The consumer thread ofthe ACM user 116 and/or the acceleration module 150 may consider memorysemantic accesses to the memory range mapped to the triggeredauto-commit buffers 1013 (e.g., the ACM memory range 1021) as being“instantly committed” as described above.

Performance of the consumer thread(s) of the ACM user 116 and/or of theacceleration module 150 may be enhanced by configuring the supplierthreads of the acceleration module 150 to allocate and/or armauto-commit buffers 1013 in advance. When a next auto-commit buffer 1013is needed, the ACM user 116 may have access to a pre-allocated/armedbuffer 1013 from a pool maintained by the supplier. The supplier mayalso perform cleanup and/or commit operations when needed. For example,if data written to an auto-commit buffer 1013 is to be committed topersistent storage 122, a supplier thread (or another thread outside ofthe write-commit path) may cause the data to be committed (e.g., usingthe SML API 132). Committing the data may comprise reallocating and/orre-arming the auto-commit buffer 1013 for a consumer thread of the ACMuser 116 as described above.

The “supplier/consumer” approach described above may be used toimplement a “rolling buffer” for transaction logs or other datastructures. An ACM user 116 may be configured to use a pre-determinedamount of “rolling” data. For example, an ACM user 116 may implement amessage queue that stores the “last 20 inbound messages” and/or the ACMuser 116 may manage directives for a non-volatile storage device (e.g.,persistent trim directives or the like). A supplier thread may allocateauto-commit buffers 1013 having at least enough capacity to hold the“rolling data” needed by the ACM user 116 (e.g., enough capacity to holdthe last 20 inbound messages). A consumer thread may access the buffers1013 using memory access semantics (load and store calls) as describedabove.

The SML API 132 (and/or supplier thread of the ACM user 116) may monitorthe use of the auto-commit buffers 1013. When the consumer thread nearsthe end of its auto-commit buffers 1013, the supplier thread mayre-initialize the “head” of the buffers 1013, by causing the data to becommitted (e.g., if necessary), mapping the data to another range withinthe memory system 1018, and arming the auto-commit buffer 1013 with acorresponding logical identifier 1025. As the consumer continues toaccess the buffers 1013, the consumer stores new data at a new locationthat “rolls over” to the auto-commit buffer 1013 that was re-initializedby the supplier thread, and continues to operate. In some cases, datawritten to the rolling buffers 1013 described above may never becommitted to persistent storage 122, 121 (e.g., unless a restartcondition or other triggering condition occurs). Moreover, if thecapacity of the auto-commit buffers 1013 is sufficient to hold therolling data of the ACM user 116, the supplier threads may not have toperform re-initialize/re-arming described above. Instead, the supplierthreads may simply re-map auto-commit buffers 1013 that comprise datathat has “rolled over” (and/or discard the “rolled over” data therein).

In its simplest form, a rolling buffer may comprise two ACM buffers1013, and the storage management layer 130 may write to one ACM buffer1013 for an ACM user 116 while destaging previously written data fromthe other ACM buffer 1013 to a storage location, such as thenon-volatile storage medium 122 or the like. In response to filling oneACM buffer 1013 and completing a destaging process of the other ACMbuffer 1013, the storage management layer 130 may transparently switchthe two ACM buffers 1013 such that the ACM user 116 writes to the otherACM buffer 1013 during destaging of the one ACM buffer 1013, in aping-pong fashion. The storage management layer 130 may implement asimilar rolling process with more than two ACM buffers 1013. Theacceleration module 150, in certain embodiments, includes and/orsupports one or more transaction log API functions. An ACM user 116 mayuse the acceleration module 150, in these embodiments, to declare orinitialize a transaction log data structure.

As a parameter to a transaction log API command to create a transactionlog data structure, based on metadata from a database system 116 a,based on an intercepted transaction log entry request, or the like, inone embodiment, the acceleration module 150 may receive a storagelocation, such as a location in a namespace and/or address space of thenon-volatile storage 122 or the like, to which the storage managementlayer 130 may commit, empty, and/or destage data of the transaction logfrom two or more ACM buffers 1013 in a rolling or circular manner asdescribed above, such as a location in the non-volatile storage medium122, a location in the non-volatile storage device 121, or the like.Once an ACM user 116 has initialized or declared a transaction log datastructure, in one embodiment, the use of two or more ACM buffers 1013 toimplement the transaction log data structure is substantiallytransparent to the ACM user 116, with the performance and benefits ofthe ACM 1011. The use of two or more ACM buffers 1013, in certainembodiments, is transparent when the destage rate for the two or moreACM buffers 1013 is greater than or equal to the rate at which the ACMuser 116 writes to the two or more ACM buffers 1013. The accelerationmodule 150, in one embodiment, provides byte-level writes to atransaction log data structure using two or more ACM buffers 1013.

In another example, a supplier thread may maintain four (4) or more ACMbuffers 1013. A first ACM buffer 1013 may be armed and ready to acceptdata from the consumer, as described above. A second ACM buffer 1013 maybe actively accessed (e.g., filled) by a consumer thread, as describedabove. A third ACM buffer 1013 may be in a pre-arming process (e.g.,re-initializing, as described above), and a fourth ACM buffer 1013 maybe “emptying” or “destaging” (e.g., committing to persistent storage122, 121, as described above).

In certain embodiments, the acceleration module 150 may provide accessto transaction log data structures as files in a file system, such asthe depicted file system module 1558. The file system module 1558, inone embodiment, may comprise a file system of the host device 110, andmay be provided by an operating system, a storage subsystem, or thelike. In a further embodiment, the file system module 1558 may comprisea direct file system (DFS) for the ACM 1011 and/or the non-volatilestorage medium 122, bypassing one or more operating system or storagesubsystem layers or the like to provide efficient, streamlined access totransaction log data structures directly.

For example, in one embodiment, the file system module 1558 may lay outfiles directly in a sparse logical address space provided by the storagemanagement layer 130, which the storage management layer 130, the filesystem module 1558, the metadata module 1912 described below, or thelike may map directly to physical locations in the ACM buffers 1013and/or the non-volatile storage medium 122. The file system module 1558,in a further embodiment, may use or cooperate with the storagemanagement layer 130 and/or the ACM 1011 to perform block allocations,ACM buffer 1013 allocations, and/or atomic data updates, each for theacceleration module 150 or other storage clients. The file system module1558 may support one or more file system interfaces or APIs such asopen, close, read, write, pread, pwrite, lseek, mmap, or other requestsor commands. The file system module 1558 may comprise a kernel module inkernel-space, a user module in user-space, or a combination of modulesin both kernel-space and user-space. The file system module 1558, incertain embodiments, may be integrated with the storage management layer130, a storage controller 104, or the like, or may be an independentmodule of computer executable program code and/or logic hardware.

As described above, the auto-commit memory module 1011, an associatedcommit agent 1020, or the like may be configured to commit, copy,transfer, synchronize, destage, persist, or preserve data from thevolatile ACM buffers 1013 to the non-volatile storage medium 122 and/orto the second non-volatile storage device 121, in response to a triggersuch as a commit event, a restart event, a synchronize or destagerequest, a change in state, a change in condition, a change in a factor,a change in an attribute, a region of an auto-commit buffer 1013becoming full, or the like based on ACM metadata 1015. Committing data,in one embodiment, may comprise copying or transferring the data from anACM buffer 1013 to a location in the non-volatile storage medium 122and/or the second non-volatile storage device 121. In a furtherembodiment, data is considered committed as soon as an ACM buffer 1013has been armed or configured with ACM metadata 1015 defining orindicating a commit action for the data, due to the auto-commit memorymodule 1011's guarantee of persistence.

The acceleration module 150, in one embodiment, may be configured toprovide data for a transaction log data structure (e.g., input data fora data structure from a client 116) to the auto-commit memory module1011 for writing to one or more ACM buffers 1013 so that the transactionlog data structure is committed and/or ensured to be persisted in thenon-volatile storage medium 122 of the non-volatile storage device 102,and/or in the second non-volatile storage device 121. The accelerationmodule 150 may use one or more ACM primitive operations to managetransaction log acceleration using the auto-commit memory module 1011.For example, in various embodiments, the acceleration module 150 may usean ACM populate operation to load data of a transaction log datastructure into an ACM buffer 1013, may use an ACM destage operation todestage, copy, transfer, and/or move data of a transaction log datastructure from an ACM buffer 1013 to the non-volatile storage medium122, may use an ACM barrier or ACM checkpoint operation to ensureconsistency of data of a transaction log data structure stored in an ACMbuffer 1013, or the like. In a further embodiment, one or more ACMbuffers 1013 may be mapped into virtual memory of the host device 110 orthe like, and the acceleration module 150 may write, store, or load datainto an ACM buffer 1013 using memory semantic operations, as describedabove.

As described above, the storage management layer 130 may be configuredto store data in the non-volatile storage medium 122 sequentially, in asequential or chronological log-based writing structure 2140 asdescribed below with regard to FIG. 6. The storage management layer 130may map logical addresses of data to physical locations storing the datain the non-volatile storage medium 122 using a logical-to-physicaladdress mapping structure 2000 as described below with regard to FIG. 6.Transaction log data structures of the acceleration module 150, incertain embodiments, may be accessible as files of the file systemmodule 1558 using file names. Transaction log data structures, files ofthe file system module 1558, or the like may be associated with logicalidentifiers (e.g., LBAs) in a logical address space provided by thestorage management layer 130, which may comprise a sparse logicaladdress space that is larger than a physical storage capacity of thenon-volatile storage device 102. The acceleration module 150, the filesystem module 1558, and/or the storage management layer 130 may trackwhich portions of a transaction log data structure, a file, or the likeare stored in the ACM buffers 1013 and which potions are stored in thenon-volatile storage medium 122 and/or in the non-volatile storagedevice 121, maintaining such mappings in file system metadata for thefile system module 1558 or the like.

In this manner, in certain embodiments, the file system module 1558 mayprovide access to a plurality of files using filenames, offsets, or thelike and the files (e.g., transaction log data structures or otherfiles) may be stored in the ACM buffers 1013, the non-volatile storagemedium 122 and/or in both the ACM buffers 1013 and the non-volatilestorage medium 122. Such cooperation between the acceleration module150, the file system module 1558, the storage management layer 130,and/or the auto-commit memory module 1011 may be hidden or masked fromapplications or other clients, who may receive the access speed of thevolatile ACM buffers 1013, the persistence of the non-volatile storagemedium 122, and the convenience of file system access to transaction logdata structures without managing or awareness of the underlyingcomplexities.

Because the file system module 1559, in certain embodiments, isconfigured to provide access to files physically located in the ACMbuffers 1013 and/or the non-volatile storage medium 122, transaction logdata structures that are associated with filenames and accessible asfiles through the file system module 1558, in one embodiment, may beaccessed (e.g., written to and/or read from) using the block deviceinterface 1520, the memory semantic interface 1522, and/or file systemoperations provided by the file system module 1558. In one embodiment,the file system module 1558 opens a file as an ACM container, with eachblock of data mapped to a location either in the ACM buffers 1013 or thenon-volatile storage medium 122, and the mapping is updated as new dataof the file is written, as data of the file is destaged from an ACMbuffer 1013 to the non-volatile storage medium 122, or the like.

In certain embodiments, instead of or in addition to using a volatilememory namespace, such as a physical memory namespace, a virtual memorynamespace, or the like and/or instead of or in addition to using astorage namespace, such as a file system namespace, a logical unitnumber (LUN) namespace, or the like, one or more commit agents 1020, asdescribed above, may implement an independent persistent memorynamespace for the ACM 1011, for associating transaction logs and/orentries with storage clients 116, or the like. For example, a volatilememory namespace, which may be accessed using an offset in physicaland/or virtual memory, is not persistent or available after a restartevent such as a reboot, failure event, or the like and a process thatowned the data in physical and/or virtual memory prior to the restartevent typically no longer exists after the restart event. Alternatively,a storage namespace may be accessed using a file name and an offset, aLUN ID and an offset, or the like. While a storage namespace may beavailable after a restart event, a storage namespace may have too muchoverhead for use with the ACM 1011. For example, saving a state for eachexecuting storage client 116 using a file system storage namespace mayresult in a separate file for each storage client 116, which may not bean efficient use of the ACM 1011.

The one or more commit agents 1020 and/or the controller 104, in certainembodiments, provide ACM users 116 with a new type of persistent memorynamespace for the ACM 1011 that is persistent through restart eventswithout the overhead of a storage namespace. One or more processes, suchas an ACM user 116, in one embodiment, may access the persistent memorynamespace using a unique identifier associated with the ACM user 116,such as a globally unique identifier (GUID), universal unique identifier(UUID), or the like so that data stored by a first process for the ACMuser 116 prior to a restart event is accessible to a second process forthe ACM user 116 after the restart event using a unique identifier,without the overhead of a storage namespace, a file system, or the like.

The unique identifier, in one embodiment, may be assigned to an ACM user116 by a commit agent 1020, the controller 104, the acceleration module150, or the like. In another embodiment, an ACM user 116 may determineits own unique identifier. In certain embodiments, the persistent memorynamespace is sufficiently large and/or ACM users 116 determine a uniqueidentifier in a predefined, known manner (e.g., based on a sufficientlyunique seed value, nonce, or the like) to reduce, limit, and/oreliminate collisions between unique identifiers. In one embodiment, theACM metadata 1015 includes a persistent memory namespace uniqueidentifier associated with an owner of an ACM buffer 1013, an owner ofone or more pages of an ACM buffer 1013, or the like, such as an ACMuser 116 (e.g., a database system 116 a).

In one embodiment, the one or more commit agents 1020, the accelerationmodule 150, and/or the controller 104 provide a persistent memorynamespace API to ACM users 116, over which the ACM users 116 may accessthe ACM 1011 using the persistent memory namespace. In variousembodiments, the one or more commit agents 1020 and/or the controller104 may provide a persistent memory namespace API function totransition, convert, map, and/or copy data from an existing namespace,such as a volatile memory namespace or a storage namespace, to apersistent memory namespace; a persistent memory namespace API functionto transition, convert, map, and/or copy data from a persistent memorynamespace to an existing namespace, such as a volatile memory namespaceor a storage namespace; a persistent memory namespace API function toassign a unique identifier such as a GUID, a UUID, or the like; apersistent memory namespace API function to list or enumerate ACMbuffers 1013 associated with a unique identifier; a persistent memorynamespace API function to export or migrate data associated with aunique identifier so that an ACM user 116 such as an application and/orprocess (e.g., a database system 116 a) may take its ACM data to adifferent host 110, to a different ACM 1011, or the like; and/or otherpersistent memory namespace API functions for the ACM 1011.

For example, an ACM user 116, in one embodiment, may use a persistentmemory namespace API function to map one or more ACM buffers 1013 of apersistent memory namespace into virtual memory of an operating systemof the host 110, or the like, and the mapping into the virtual memorymay end in response to a restart event while the ACM user 116 maycontinue to access the one or more ACM buffers 1013 after the restartevent using the persistent memory namespace. In certain embodiments, thestorage management layer 130 and/or the acceleration module 150 mayprovide the persistent memory namespace API in cooperation with the oneor more commit agents 1020 and/or the controller 104.

The persistent memory namespace, in certain embodiments, is a flatnon-hierarchical namespace of ACM buffers 1013 (and/or associated ACMpages), indexed by the ACM metadata 1015. The one or more commit agents1020, the acceleration module 150, and/or the controller 104, in oneembodiment, allow the ACM buffers 1013 to be queried by ACM metadata1015. In embodiments where the ACM metadata 1015 includes a uniqueidentifier, in certain embodiments, an ACM user 116 may query or searchthe ACM buffers 1013 by unique identifier to locate ACM buffers 1013(and/or stored data, such as a transaction log) associated with a uniqueidentifier. In a further embodiment, the one or more commit agents 1020and/or the controller 104 may provide one or more generic metadatafields in the ACM metadata 1015 such that an ACM user 116 may define itsown ACM metadata 1015 in the generic metadata field, or the like. Theone or more commit agents 1020, the acceleration module 150, and/or thecontroller 104, in one embodiment, may provide access control for theACM 1011, based on unique identifiers, or the like.

In one embodiment, an ACM buffer 1013 may be a member of a persistentmemory namespace and one or more additional namespaces, such as avolatile namespace, a storage namespace or the like. In a furtherembodiment, the one or more commit agents 1020, the acceleration module150, and/or the controller 104 may provide multiple ACM users 116 withsimultaneous access to the same ACM buffers 103. For example, multipleACM users 116 of the same type and/or with the same unique identifier,multiple instances of a single type of ACM user 116, multiple processesof a single ACM user 116, or the like may share one or more ACM buffers1013. Multiple ACM users 116 accessing the same ACM buffers 1013, in oneembodiment, may provide their own access control for the shared ACMbuffers 1013, such as a locking control, turn-based control,moderator-based control, or the like.

FIG. 5A depicts one embodiment of an acceleration module 150. Theacceleration module 150, in certain embodiments, may be substantiallysimilar to the various embodiments of the acceleration module 150described above. In other embodiments, the acceleration module 150 mayinclude, may be integrated with, and/or may be in communication with thestorage management layer 130, the storage controller 104, and/or thecommit agent 1020.

In general, the acceleration module 150 stores transaction log datastructure entries from a storage client 116 such as a database system116 a in a volatile memory 1013 of the ACM 1011, at least temporarily,to accelerate storage of the transaction log data structure entries. Inthe depicted embodiment, the acceleration module 150 includes a logmodule 1902, a commit module 1904, and a storage module 1906.

As described above, in certain embodiments, the acceleration module 150and/or the ACM 1011 enable clients such as the ACM users/storage clients116 to access transaction log data structures using fast,byte-addressable, persistent memory, combining benefits of volatilememory and non-volatile storage for persisting data structures.Auto-commit logic inside the hardware of the non-volatile storage device102, such as the auto-commit memory 1011 described above, in certainembodiments, provides power-cut protection for data structures writtento the auto-commit buffers 1013 of the ACM 1011. The acceleration module150 and/or its sub-modules, in various embodiments, may at leastpartially be integrated with a device driver (e.g., a softwarecontroller) executing on the processor 111 of the host computing device110 such as the storage management layer 130, may at least partially beintegrated with a hardware controller 104 of the ACM 1011 and/ornon-volatile storage device 102, as microcode, firmware, logic circuits,or the like, or may be divided between a device driver and a hardwarecontroller 104, 104, or the like.

In one embodiment, the log module 1902 is configured to determine one ormore transaction log records (e.g., database log entries, journalrecords, or the like) indicating a sequence of operations performed ondata, such as database records, database tables, files, metadata, userdata, management data, or the like. In certain embodiments, the logmodule 1902 is part of or cooperates with a storage client 116 (e.g., adatabase system 116 a) to generate transaction log records based on oneor more events, transactions, and/or operations of the storage client116. For example, a storage client 116, such as a database system 116 aor the like, may be aware of, configured to use, and/or compatible withthe acceleration module 150 and/or the ACM 1011, and may provide one ormore transaction log records (e.g., database log entries, journalrecords, or the like) directly to the log module 1902.

In a further embodiment, the log module 1902 may intercept, filter, orotherwise monitor one or more transaction log records sent by a storageclient 116 such as a database system 116 a or the like (e.g., withoutknowledge of the storage client 116). For example, a storage client 116may send one or more transaction log records (e.g., database logentries, journal records, or the like) to the non-volatile storagedevice 121 or another different location (e.g., using the block I/Ointerface 131 or the like) and the log module 1902 may intercept,filter, or otherwise monitor the one or more transaction log records. Inthis manner, in certain embodiments, the log module 1902 may allowstorage clients 116 which are not natively compatible with and/or awareof the ACM 1011 to receive the benefits of the ACM 1011 for acceleratingstorage of transaction log records. The log module 1902 may intercept orotherwise receive transaction log records using an existing or standardinterface, using a filter driver, overloading an interface, usingLD_PRELOAD, intercepting or trapping a segmentation fault, using anIOCTL command, using a custom transaction log interface, or the like.

In certain embodiments, the log module 1902 may be configured tointercept, filter, or otherwise monitor transaction log records,database log entries, journal records, or the like according to one ormore characteristics. For example, the log module 1902 may intercept,filter, and/or monitor each transaction log record from one or moreselected storage clients 116, of a predefined type or class, destinedand/or addressed for a selected location (e.g., for the non-volatilestorage device 121, for the non-volatile storage medium 122, for a rangeof one or more logical addresses, or the like), and/or based on one ormore other characteristics. In one embodiment, the one or morecharacteristics are user configurable and/or selectable, through a userinterface such as a GUI, a CLI, a configuration file, or the like.

At least a portion of the log module 1902 may be part of, integratedwith, and/or in communication with the storage management layer 130, adevice driver for the non-volatile storage device 102 and/or for thenon-volatile storage device 121 or other controller executing on thehost computing device 110, a filter driver, an operating system, a filesystem, or the like of the host computing device 110. In anotherembodiment, the log module 1902 may comprise software, firmware, and/orlogic hardware of a device located on the network 115, such as a networkinterface card (NIC), a router, a switch, a modem, a firewall, a networkappliance, or the like.

The log module 1902, in certain embodiments, provides an interfacewhereby an application 116 or other storage client 116 (e.g., a databasesystem 116 a) may access transaction log data structures stored in theACM buffers 1013 and/or the non-volatile storage medium 122, whether theACM buffers 1013 are natively volatile or non-volatile, regardless ofthe type of medium used for the ACM buffers 1013, regardless of whetherthe data structures are stored in the ACM buffers 1013, the non-volatilestorage medium 122, or a combination of both the ACM buffers 1013 andthe non-volatile storage medium 122.

Instead of or in addition to the above methods of accessing the ACM1011, such as using a memory map (e.g., mmap) interface, in certainembodiments, the log module 1902 may use the ACM 1011 to exposetransaction log data structures to applications or other clients usingan API, shared library, file system namespace or other persistentlogical identifiers, or the like as described above. The log module1902, in certain embodiments, may bypass one or more operating systemand/or kernel layers, which may otherwise reduce performance of the ACM1011, complicate access to transaction log data structures, or the like,increasing access times, introducing delays, or the like. The log module1902, in various embodiments, may provide access to transaction log datastructures using an existing I/O interface or namespace, such as astandard read/write API, a file system namespace, a LUN namespace, orthe like or may provide a custom transaction log interface.

In one embodiment, the log module 1902 is configured to monitor, detect,intercept, or otherwise receive requests for transaction log datastructures from applications or other clients, such as the ACMusers/storage clients 116 described above, another module, a hostcomputing device 110, or the like (e.g., instead of or in addition tofiltering or intercepting transaction log entries). The log module 1902may receive data requests over an API, a shared library, acommunications bus, the SML interface 132, or another interface. As usedherein, a data request may comprise a storage request, a memory request,a file request, a transaction log request, an auto-commit request, orthe like to access a data structure, such as an open, write/append,synchronize, close, map, and/or transaction log allocation request.

As described below with regard to the identifier module 1910, in certainembodiments, a transaction log data structure and/or a storage client116 may be associated with a persistent logical identifier. Accordingly,a transaction log request may include a persistent logical identifier ofthe associated transaction log data structure. A logical identifier, inone embodiment, is a member of a namespace. As used herein, a namespacecomprises a container or range of logical or physical identifiers thatindex or identify data, data locations, data structures, or the like. Asdescribed above, examples of namespaces may include a file systemnamespace, a LUN namespace, a logical address space, a storagenamespace, a virtual memory namespace, a persistent ACM namespace, avolatile memory namespace, an object namespace, a network namespace, aglobal or universal namespace, a BAR namespace, or the like.

A logical identifier may indicate a namespace to which a data structurebelongs. In one embodiment, a logical identifier may comprise a filename or other file identifier and/or an offset from a file systemnamespace, a LUN ID and an offset from a LUN namespace, an LBA or LBArange from a storage namespace, one or more virtual memory addressesfrom a virtual memory namespace, an ACM address from a persistent ACMnamespace, a volatile memory address from a volatile memory namespace ofthe host device 110, an object identifier, a network address, a GUID,UUID, or the like, a BAR address or address range from a BAR namespace,or another logical identifier. In a further embodiment, a logicalidentifier may comprise a label or a name for a namespace, such as adirectory, a file path, a device identifier, or the like. In anotherembodiment, a logical identifier may comprise a physical address orlocation for a data structure. As described above, certain namespaces,and therefore namespace identifiers, may be temporary or volatile, andmay not be available to an ACM user/storage client 116 or other clientafter a restart event. Other namespaces, and associated logicalidentifiers, may be persistent, such as a file system namespace, a LUNnamespace, a persistent ACM namespace, or the like, and data structuresassociated with the persistent namespace may be accessible to an ACMuser/storage client 116 after a restart event using the persistentlogical identifier.

The log module 1902, in one embodiment, may receive an open request froma client to open or initialize a transaction log data structure. In afurther embodiment, the log module 1902 may receive a write request(e.g., for a transaction log data structure, an append request) from aclient to write and/or append data to a transaction log data structure,using the ACM buffers 1013 or the like. The log module 1902, in anotherembodiment, may receive a synchronize request, a destage request, or thelike to trigger copying, destaging, transferring, migrating, orsynchronization of a data structure from an ACM buffer 1013 to thenon-volatile storage medium 122, to the non-volatile storage device 121,or the like. The log module 1902, in one embodiment, may receive a closerequest from a client to close, lock, delete, clear, or otherwise finisha data structure. In a further embodiment, the log module 1902 mayreceive a map request to map a region of ACM 1011 (e.g., one or more ACMbuffers 1013, pages, cache lines, memory locations, ranges of memorylocations, or the like) into virtual memory of the storage client 116 onthe host device 110. The log module 1902, in another embodiment, mayreceive an allocation request to allocate one or more regions of the ACM1011 for storing a data structure, a portion of a data structure, or thelike.

The log module 1902, in certain embodiments, may receive transaction logrequests in user-space. As used herein, kernel-space may comprise anarea of memory (e.g., volatile memory, virtual memory, main memory) ofthe host computing device 110; a set of privileges, libraries, orfunctions; a level of execution; or the like reserved for a kernel,operating system, or other privileged or trusted processes orapplications. User-space, as used herein, may comprise an area of memory(e.g., volatile memory, virtual memory, main memory) of the hostcomputing device 110; a set of privileges, libraries, or functions; alevel of execution; or the like available to untrusted, unprivilegedprocesses or applications.

Due to access control restrictions, privilege requirements, or the likefor kernel-space, providing a device driver, library, API, or the likefor the ACM 1011 in kernel-space may have greater delays than inuser-space. Further, use of a storage stack of a kernel or operatingsystem, in certain embodiments, may introduce additional delays. Anoperating system or kernel storage stack, as used herein, may compriseone or more layers of device drivers, translation layers, file systems,caches, and/or interfaces provided in kernel-space, for accessing a datastorage device. The acceleration module 150, in certain embodiments, mayprovide direct access to transaction log data structures and/or to theACM 1011 by bypassing and/or replacing one or more layers of anoperating system or kernel storage stack, reading and writing datastructures directly between the ACM buffers 1013 and/or the non-volatilestorage medium 122 and user-space or the like. In a further embodiment,the log module 1902 may receive transaction log requests in user-spacefrom user-space applications 116 or other storage clients 116 and inkernel-space from kernel-space applications 116 or other storage clients116.

In one embodiment, the commit module 1904 is configured to send one ormore transaction log records (e.g., from the log module 1902) to one ormore volatile memory pages 1013 accessible over the network 115. Asdescribed above, the volatile memory pages 1013 may be configured toensure persistence of data written to the volatile memory 1013, such astransaction log records. The commit module 1904 may write one or moretransaction log records to the volatile memory 1013 (e.g., ACM buffers1013) using RDMA, Infiniband, memory access semantics, CPU load/storecommands, DMA commands, 3rd party DMA commands, atomic test and setcommands, manipulatable memory pointers, network requests, PCI-e BAR, orthe like. As described above, writing data to the volatile memory 1013over the network 115 may have a lower latency than writing data directlyto the non-volatile storage medium 122; to local storage of the hostcomputing device 110, if any; to the non-volatile storage device 121; orthe like, because the ACM 1011 may have the low latency of volatilememory 1013 (e.g., RAM) and the ensured persistence of the non-volatilestorage medium 122.

In one embodiment, the commit module 1904 is configured to receive,retrieve, transfer, or otherwise process input data (e.g., transactionlog entries) from a client 116 for writing, updating, or appending to atransaction log data structure. For example, a write request or appendrequest received by the log module 1902 may include or reference data tobe written or appended to a transaction log data structure identified bythe request, which the commit module 1904 may use to write the data tothe ACM buffers 1013. In one embodiment, the commit module 1904 maywrite data of write requests to the ACM buffers 1013 itself. In anotherembodiment, the commit module 1904 may monitor one or more regions ofthe ACM buffers 1013 or may receive an alert/notification that a client116 has written data to the one or more regions of the ACM buffers 1013,or the like.

In one embodiment, a write request, a transaction log request, or thelike may indicate where in a transaction log data structure theassociated data is to be written (e.g., to which node, field, row,column, entry, or the like). In other embodiments, a location for datamay be defined by a rule, definition, or schema for a type oftransaction log data structure, such as an append-only persistenttransaction log or the like. A write request, append request, or thelike, in one embodiment, may include data structure metadata to bewritten with the associated write data (e.g., a timestamp, a sequencenumber, a label, an identifier, a pointer, or the like). In anotherembodiment, the commit module 1904 may determine data structure metadatato be written with associated write data based on a state of atransaction log data structure, based on metadata for a transaction logdata structure from the metadata module 1912, by incrementing a pointer,a sequence number, or an identifier for a transaction log datastructure, or the like.

The commit module 1904, in certain embodiments, may write data to a datastructure, store data in a data structure, append data to a datastructure, or the like by writing or storing the data into a region ofthe ACM buffers 1013, which may guarantee or ensure persistence of thedata should a failure condition, restart event, or other trigger occur.In certain embodiments, if a transaction log data structure has not beenallocated a memory region in the ACM buffers 1013 or the like, thecommit module 1904 may write data of a transaction log data structure tothe non-volatile storage medium 122. In other embodiments, the commitmodule 1904 may cooperate with the identifier module 1910 and/or theauto-commit memory module 1011 to allocate a memory region of the ACMbuffers 1013 to a transaction log data structure in response to a writerequest, an append request, or the like for the transaction log datastructure.

The commit module 1904 may cooperate with the metadata module 1912, thefile system module 1558, the storage management layer 130, and/or theauto-commit memory module 1011 to update logical-to-physical mappings,file system metadata, or the like for one or more logical identifiers ofan updated transaction log data structure. For example, in response toan append request for a transaction log, the commit module 1904 and/orthe metadata module 1912 may extend a file length associated with a fileof the transaction log by the file system module 1558, add an entry in alogical-to-physical mapping structure mapping a range of LBAs for theupdated data to a location in the ACM buffers 1013 storing the data,increment a pointer identifying an append point of the transaction log,or the like.

To provide the fast write times of the ACM buffers 1013 to applications116 or other storage clients 116 writing to transaction log datastructures, even with relatively small amounts or capacities of ACMbuffers 1013, in one embodiment, the commit module 1904 may cooperatewith the storage module 1906 described below to use memory regions ofthe ACM buffers 1013 as a ring buffer, a ping-pong buffer, a rollingbuffer, a sliding window, or the like, alternating between differentmemory regions of the ACM buffers 1013 for writing data of a transactionlog data structure, while the storage module 1906 destages, copies, ortransfers data from a memory region not being written to. In thismanner, the commit module 1904 may reuse or overwrite a region of memoryof the ACM buffers 1013 only after the storage module 1906 has alreadydestaged, copied, transferred, committed, or otherwise persisted thepreviously written data, providing efficient use of the ACM buffers 1013while still ensuring persistence.

In other embodiments, the storage module 1906 does not destagetransaction log entries from the non-volatile storage device 102 (e.g.,destaging transaction log entries may require additional informationregarding an associated storage client 116, an original targetdestination for the transaction log entries, or the like), and theassociated storage client 116 and/or the storage module 1906 may insteadwrite the transaction log entries from the host computing device 110 tothe non-volatile storage device 121, in response to the commit module1904 storing the transaction log entries in the volatile memory 1013.The commit module 1904 may clear, erase, delete, flush, trim, evict, orotherwise remove one or more transaction log entries (e.g., database logrecords, journal records) from the non-volatile storage device 102(e.g., the volatile memory 1013 and/or the non-volatile storage medium122), in response to the non-volatile storage device 121 storing the oneor more transaction log entries, to free storage capacity for additionaltransaction log entries or other data.

In one embodiment, the storage module 1906 is configured to send one ormore transaction log records to the non-volatile storage device 121. Forexample, the storage module 1906 may send one or more transaction logrecords to the non-volatile storage device 121 in response to anacknowledgment from the non-volatile storage device 102 that one or morevolatile memory pages 1013 and/or the non-volatile storage medium 122store the one or more transaction log records.

In one embodiment, the storage module 1906 stores, caches, and/orbuffers one or more transaction log entries received by the log module1902 until the storage module 1906 receives an acknowledgment that thevolatile memory 1013 and/or the non-volatile storage medium 122 storethe one or more transaction log entries, so that the storage module 1906may write the one or more transaction log entries to the non-volatilestorage device 121 directly from the host computing device 110, insteadof reading the one or more transaction log entries from the non-volatilestorage device 102. In a further embodiment, in response to a restartevent or other trigger (e.g., a power interruption event) causing thestorage module 1906 to lose one or more transaction log entries (e.g.,the storage module 1906 failing to send the one or more transaction logentries to the non-volatile storage device 121 prior to the trigger),the storage module 1906 may receive the one or more transaction logentries from the non-volatile storage device 102 (e.g., from thevolatile memory 1013 and/or from the non-volatile storage medium 122)and may send the received one or more transaction log entries from thenon-volatile storage device 102 to the non-volatile storage device 121after recovery from the restart event or other trigger (e.g., a powerinterruption event), as described below with regard to the recoverymodule 1908.

The storage module 1906, in certain embodiments, may send and/or writethe one or more transaction log entries to an original target locationfor the one or more transaction log entries, such as a location to whichthe storage client 116 originally sent the one or more transaction logentries, before the log module 1902 intercepted and/or filtered the oneor more transaction log entries. For example, a database system 116 a orother storage client 116 may send one or more transaction log entriesfor storage in the second/different non-volatile storage device 121 andthe log module 1902 may intercept and/or filter the one or moretransaction log entries before they are sent to and/or written to thenon-volatile storage device 121, as described above. The storage module1906 may hold or queue the one or more intercepted/filtered transactionlog entries until the commit module 1904 stores the one or moretransaction log entries in the volatile memory 1013 and/or thenon-volatile storage medium 122, in response to which the storage module1906 may send and/or write the one or more transaction log entries totheir originally intended destination in the non-volatile storage device121.

In embodiments where the storage module 1906 sends one or moretransaction log entries to the non-volatile storage device 121 from thehost computing device 110, at least a portion of the storage module 1906may be part of, integrated with, and/or in communication with thestorage management layer 130, a device driver for the non-volatilestorage device 102 and/or for the non-volatile storage device 121 orother controller executing on the host computing device 110, a filterdriver, an operating system, a file system, or the like executing on thehost computing device 110. In this manner, in certain embodiments, thenon-volatile storage device 102, the non-volatile storage mediumcontroller 104, and/or the ACM 1011 may have little or no knowledge ofthe non-volatile storage device 121, of original target destinations forone or more transaction log entries, settings and/or preferences of astorage client 116, or the like.

In a further embodiment, the storage module 1906 may be at leastpartially disposed on the non-volatile storage device 102, as part ofthe non-volatile storage medium controller 104, the ACM 1011, or thelike (e.g., hardware logic, firmware, microcode, computer executableinstructions stored on a non-transitory computer readable medium, anFPGA, an ASIC, or the like). The commit module 1904, in such anembodiment, may send a target location from a storage client 116 for oneor more transaction log entries, to the storage module 1906 on thenon-volatile memory device 102, with the one or more transaction logentries or the like. For example, the commit module 1904 may send alogical identifier (e.g., a range of one or more LBAs or the like), aphysical address, or the like for the one or more transaction logentries to be stored in the non-volatile storage device 121. In responseto storing the one or more transaction log entries in the volatilememory 1013, the storage module 1906, in such an embodiment, may sendthe one or more transactional log entries from the non-volatile storagedevice 102 to the location in the non-volatile storage device 121, overthe network 115 or the like.

In one embodiment, the storage module 1906 may be configured to destagedata from the ACM buffers 1013 to the non-volatile storage medium 122,such as transaction log data structure data that the commit module 1904has written to the ACM buffers 1013 as described above. The storagemodule 1906, in certain embodiments, cleans or destages data of the ACMbuffers 1013 that the non-volatile storage medium 122 and/or thenon-volatile storage device 121 does not yet store, such as new data,updated data, or the like. A location for the data in the non-volatilestorage medium 122, such as an LBA, a physical address, or the like, maybe indicated by ACM metadata 1015 or other triggered commit metadata asdescribed above. The storage module 1906, in certain embodiments,copies, transfers, destages, moves, or writes data from the ACM buffers1013 to the non-volatile storage medium 122 itself, based on ACMmetadata 1015, a dirty data bitmap, transaction log metadata from themetadata module 1912, or the like.

In a further embodiment, the storage module 1906 may cause data to becopied, transferred, destaged, moved, or written from the ACM buffers1013 to the non-volatile storage medium 122, by triggering theauto-commit memory module 1011, a commit agent 1020, a commit agent1020, or the like to perform a commit action for the data identified ordefined by ACM metadata 1015 for the data. For example, as describedabove, the auto-commit buffers 1013 may be armed with ACM metadata 1015to perform a commit action for preserving or persisting stored data. Thestorage module 1906 may utilize this pre-arming for destaging,committing, or transferring data from the auto-commit buffers 1013 tothe non-volatile storage medium 122.

While the commit module 1904, in certain embodiments, may operate as aforeground process, writing data or allowing data to be written to theACM buffers 1013 in the foreground, the storage module 1906, in certainembodiments, may operate as a background process. For example, in oneembodiment, the storage module 1906 may destage, copy, transfer, move,or synchronize data periodically, lazily, during system downtime, duringa period of low traffic, or the like. In one embodiment, the storagemodule 1906 may destage, copy, transfer, move, or synchronize data inresponse to a trigger. The trigger may be the same or substantiallysimilar to the trigger for a commit action described above with regardto the ACM metadata 1015. In a further embodiment, the commit module1904 may trigger the storage module 1906 based on an input rate, therebycontrolling a transfer rate of the storage module 1906.

The storage module 1906, in another embodiment, may be triggered inresponse to an amount of data of a transaction log data structure storedin a region of the ACM buffers 1013 exceeding a predefined threshold.For example, if the ACM buffers 1013 are organized into 4 KB pages, thestorage module 1906 may be triggered in response to the commit module1904 filling a 4 KB page to destage, copy, transfer, or move the datafrom the 4 KB page to the non-volatile storage medium 122. In anotherembodiment, the storage module 1906 may be triggered in response to thecommit module 1904 writing an amount of data equal to a page size orother region size of the non-volatile storage medium 122, based on anarchitecture of the non-volatile storage medium 122 or the like. In afurther embodiment, the storage module 1906 may be triggeredperiodically, in response to an elapsed time period since a previoustrigger or the like. In one embodiment, the storage module 1906 may betriggered by a monitoring device or monitoring module associated withthe memory of the ACM buffers 1013, such as the commit module 1904, theauto-commit memory module 1011, or another module. In a furtherembodiment, the storage module 1906 may be triggered by asynchronization request, a destage request, or the like that the logmodule 1902 receives from a client 116. The storage module 1906, infurther embodiments, may be triggered by another determined change instate, change in condition, factor, or attribute of memory of the one ormore ACM buffers 1013. In other embodiments, the storage module 1906does not destage data from the volatile memory 1013 to the non-volatilememory medium 122, but recovers storage capacity of the volatile memory1013 by sending the data to the second non-volatile storage device 121,as described above.

In one embodiment, the storage module 1906 may copy, destage, transfer,or write data from a memory region of the ACM buffers 1013 to thenon-volatile storage medium 122 in a manner that preserves anassociation of the data with a logical identifier of the transaction logdata structure, as described below with regard to the identifier module1910. For example, the storage module 1906 may write a storage client116 identifier, a transaction log identifier, a transaction log entryidentifier, a filename, a range of logical addresses, or another logicalidentifier to the non-volatile storage medium 122 with the data, mayupdate a logical-to-physical mapping structure with a new physicallocation for the data, may provide a new physical location for the datato the SML 130, may update file system metadata indicating that the datais stored in the non-volatile storage medium 122, or the like. Byensuring that data remains associated with a persistent logicalidentifier, in certain embodiments, the storage module 1906 ensures thatthe transaction log data structure remains accessible to a client 116using the persistent logical identifier.

As described above with regard to the commit module 1904, the storagemodule 1906 and the commit module 1904 may cooperate to use two or moreregions of the ACM buffers 1013 as a ring buffer, a ping-pong buffer, arolling buffer, a sliding window, or the like, alternating betweendifferent memory regions of the ACM buffers 1013 for storing data of atransaction log data structure, while the commit module 1904 writes datato a memory region from which the storage module 1906 is not currentlywriting data to the non-volatile storage device 121, making efficientuse of the ACM buffers 1013 while still ensuring persistence.

FIG. 5B depicts another embodiment of an acceleration module 150. In oneembodiment, the acceleration module 150 may be substantially similar toone or more of the acceleration modules 150 described above. In thedepicted embodiment, the acceleration module 150 of FIG. 5B includes alog module 1902, a commit module 1904, a storage module 1906 and furtherincludes a recovery module 1908, an identifier module 1910, and amigration module 1912.

In one embodiment, the recovery module 1908 is configured to retrieveand/or receive one or more transaction log records (e.g., database logentries, journal records, or the like) persisted in the non-volatilestorage medium 122 from the one or more volatile memory pages, inresponse to recovery from a restart event, a power interruption event,and/or another trigger. The recovery module 1908, in certainembodiments, may be substantially similar to the commit agent 1020and/or the commit module 1320 described above.

In one embodiment, the recovery module 1908 retrieves one or moretransaction log records from the non-volatile storage medium 122 andstores the one or more transaction log records in the volatile memory1013 after a restart event, a power interruption event, and/or anothertrigger. For example, the recovery module 1908 may return the volatilememory 1013 to its state prior to the restart event, power interruptionevent, and/or another trigger. In a further embodiment, the recoverymodule 1908 may receive an identifier for a transaction log, anidentifier for one or more transaction log entries, an identifier of astorage client 116, or the like, from the storage client 116, from thestorage module 1906, and/or from another entity, may retrieve one ormore transaction log entries from the non-volatile memory medium 122based on the identifier, and may provide the retrieved one or moretransaction log entries to the requesting entity (e.g., the storageclient 116, the storage module 1906, and/or another entity), for storagein the second/different non-volatile storage device 121, or the like.

The recovery module 1908, in one embodiment, may map a receivedidentifier to a location (e.g., a logical address such as an LBA, aphysical address, or the like) in the non-volatile storage medium 122(e.g., using a hash function or other predefined transform, using alogical-to-physical mapping structure or other metadata 135, or thelike) from which to retrieve the one or more transactional log entries.In a further embodiment, the recovery module 1908 may scan datapersisted from the volatile memory 1013 into the non-volatile storagemedium 122 (e.g., most recently written data, a range of data flushedand/or committed after a restart event or other trigger, or the like) tolocate data associated in the non-volatile storage medium 122 with thereceived identifier. By retrieving one or more transaction log entriesfrom the non-volatile storage medium 122 after a restart event, powerinterruption event, and/or another trigger, the recovery module 1908 mayenable the storage module 1906 to send the one or more transaction logentries to the non-volatile storage device 121, even if the storagemodule 1906 failed to send the one or more transaction log entries tothe non-volatile storage device 121 prior to the trigger.

In embodiments where the recovery module 1908 sends one or more uniqueidentifiers to the non-volatile storage device 102 from the hostcomputing device 110, at least a portion of the recovery module 1908 maybe part of, integrated with, and/or in communication with the storagemanagement layer 130, a device driver for the non-volatile storagedevice 102 and/or for the non-volatile storage device 121 or othercontroller executing on the host computing device 110, a filter driver,an operating system, a file system, or the like executing on the hostcomputing device 110. In a further embodiment, the recovery module 1908may be at least partially disposed on the non-volatile storage device102, as part of the non-volatile storage medium controller 104, the ACM1011, or the like (e.g., hardware logic, firmware, microcode, computerexecutable instructions stored on a non-transitory computer readablemedium, an FPGA, an ASIC, or the like) to receive a unique identifier(e.g., in cooperation with the identifier module 1910), to retrieve oneor more transaction log entries from the non-volatile storage medium122, or the like.

In one embodiment, the identifier module 1910 is configured to associatea transaction log, one or more transaction log records, a storage client116 (e.g., a database system 116 a), or the like with a uniqueidentifier. As described above, the recovery module 1908, in certainembodiments, may be configured to receive and/or retrieve one or morepersisted transaction log records from the non-volatile storage medium122 and/or the volatile memory 1013 based on a unique identifierassigned and/or maintained by the identifier module 1910. The identifiermodule 1910 may assign unique logical identifiers to transaction logs,to transaction log entries, and/or to storage clients 116.

The volatile memory buffer 1013 and/or the non-volatile storage medium122 may receive and/or store different transaction log entries (e.g.,database log entries) from multiple different storage clients 116 (e.g.,database systems 116 a), over the network 115 or the like, and theidentifier module 1910 may associates the different transaction logentries (e.g., database log entries) in the volatile memory buffer 1013and/or in the non-volatile storage medium 122 with different identifiersfor the multiple different storage clients 116 (e.g., database systems116 a), different identifiers for the different transaction logs,different identifiers for the different transaction log entries, or thelike.

In certain embodiments, the identifier module 1910 may be configured toinitialize or open a new transaction log data structure. For example,the identifier module 1910 may initialize or open a transaction log datastructure in response to a request received by the log module 1902, suchas an open request or the like. The identifier module 1910, in certainembodiments, may associate a logical identifier with an opened orinitialized transaction log data structure. For example, the identifiermodule 1910 may cooperate with the file system module 1558 to assign afilename to a transaction log data structure, may cooperate with thestorage management layer 130 to assign a range of logical identifierssuch as LBAs to a transaction log data structure, may cooperate with theauto-commit memory module 1011 to assign a persistent ACM identifier toa transaction log data structure, or the like. In certain embodiments,the log module 1902 may receive a logical identifier, such as afilename, a range of LBAs, a LUN ID, or the like for a transaction logdata structure as a parameter of an open request, or the like. In afurther embodiment, the identifier module 1910, the file system module1558, the storage management layer 130, the auto-commit memory module1011, or the like may assign a next available logical identifier to atransaction log data structure or may use another predetermined or knownmethod to assign a unique logical identifier.

The identifier module 1910, in one embodiment, may allocate a region ofmemory of the auto-commit memory module 1011 (e.g., of volatile memory1013 and/or non-volatile storage media 122) for storing a transactionlog data structure. As used herein, a region of memory may comprise amemory page, a memory buffer, a range of memory addresses, a memoryelement, a memory module, and/or another subset of one or more ACMbuffers 1013 and/or non-volatile storage media 122 available to theauto-commit memory module 1011. In one embodiment, the identifier module1910 may allocate a region of memory of the ACM buffers 1013 and/ornon-volatile storage medium 122 for each requested transaction log datastructure. In a further embodiment, the identifier module 1910 maycooperate with the auto-commit memory module 1011 to dynamicallyallocate available memory of the ACM buffers 1013 and/or thenon-volatile storage medium 122, allocating memory to transaction datastructures as they are accessed, based on a frequency of access, a mostrecent access, an access history, an input rate or write rate, or thelike for the different transaction log data structures.

In one embodiment, at least a portion of the identifier module 1910 maybe part of, integrated with, and/or in communication with the storagemanagement layer 130, a device driver for the non-volatile storagedevice 102 and/or for the non-volatile storage device 121 or othercontroller executing on the host computing device 110, a filter driver,an operating system, a file system, or the like executing on the hostcomputing device 110. In a further embodiment, the identifier module1910 may be at least partially disposed on the non-volatile storagedevice 102, as part of the non-volatile storage medium controller 104,the ACM 1011, or the like (e.g., hardware logic, firmware, microcode,computer executable instructions stored on a non-transitory computerreadable medium, an FPGA, an ASIC, or the like).

In one embodiment, the migration module 1912 is configured to migrate astorage client 116 (e.g., an application 116, a database system 116 a)associated with a transaction log to a different host computing device110. For example, a storage client 116 (e.g., an application 116, adatabase system 116 a) executing on a different host computing device110 than a host computing device 110 from which a transaction log wasopened and/or initiated, a user, or the like may send a uniqueidentifier for the storage client 116 and/or for a transaction log ofthe storage client 116 to the migration module 1912, from the differenthost computing device 110, with an identifier or address for thedifferent host computing device 110, or the like.

The migration module 1912 may retrieve configuration information for thestorage client 116 based on the received unique identifier, such as oneor more locations where data for the storage client 116 is stored in thenon-volatile storage device 102 and/or the different/second non-volatilestorage device 121 (e.g., settings, transaction log data, computerexecutable program code of the storage client 116, or the like). Thestorage client 116, in certain embodiments, may begin executing on thedifferent host computing device 110, based on configuration informationsaved for the storage client 116 from the original host computing device110. In this manner, in certain embodiments, the migration module 1912may allow different host computing devices 110 to operate in a failoverconfiguration, replacing another host computing device 110 by executinga storage client 116 with a saved execution state, transaction log, orthe like; may allow for a simple upgrade and migration to a new hostcomputing device 110; and/or another migration over the network 115.

In one embodiment, at least a portion of the migration module 1912 maybe part of, integrated with, and/or in communication with the storagemanagement layer 130, a device driver for the non-volatile storagedevice 102 and/or for the non-volatile storage device 121 or othercontroller executing on the host computing device 110, a filter driver,an operating system, a file system, or the like executing on the hostcomputing device 110. For example, a user may install at least a portionof the migration module 1912 on the new or different host computingdevice 110, to assist in migrating the storage client 116. In a furtherembodiment, the migration module 1912 may be at least partially disposedon the non-volatile storage device 102, as part of the non-volatilestorage medium controller 104, the ACM 1011, or the like (e.g., hardwarelogic, firmware, microcode, computer executable instructions stored on anon-transitory computer readable medium, an FPGA, an ASIC, or the like),in order to retrieve the configuration information for the storageclient 116 based on the received unique identifier, or the like.

FIG. 6 depicts one embodiment of a method 2200 for transaction logacceleration. The method 2200 begins, and the log module 1902 determines2202 one or more transactional log records, such as database log recordsor the like, for a storage client 116 (e.g., a database system 116 a)executing on a host computing device 110. The commit module 1904 sends2204 the determined 2202 one or more transactional log records to one ormore volatile memory pages 1013 over the network 115. In response to theone or more volatile memory pages 1013 storing the one or moretransactional log records, the storage module 1906 sends 2206 thedetermined 2202 one or more transactional log records to a non-volatilestorage device 121 over the network 115 and the method 2200 ends.

FIG. 7 depicts another embodiment of a method 2300 for transaction logacceleration. The method 2300 begins, and the storage controller 104receives 2302 a transaction log entry over the network 115. The storagecontroller 104 stores 2304 the received 2302 transaction log entry involatile memory 1013 of the non-volatile storage device 102. In responseto detecting 2306 a trigger, such as a power level failing to satisfy athreshold or another restart event, the storage controller 104 stores2308 the received 2302 transaction log entry in the non-volatile memorymedium 122 of the non-volatile storage device 102.

After the detected 2306 trigger (e.g., during a recovery stage for arestart event or the like), the storage controller 104 determines 2310whether an identifier for the storage client 116 has been received. Ifthe storage controller 104 determines 2310 that a valid identifier forthe storage client 116 has been received, the storage controller 104retrieves 2312 the transaction log entry from the non-volatile memorymedium 122 of the non-volatile storage device 102 and the method 2300ends. In certain embodiments, the storage controller 104 may provide theretrieved 2312 transaction log entry to the storage client 116, to therecovery module 1908, or the like for storage in a differentnon-volatile storage device 121.

FIG. 8 depicts another embodiment of a method 2400 for transaction logacceleration. The method 2400 begins, and the log module 1902 executingon the host computing device 110 intercepts 2402 one or more databaselog entries from a database system 116 a executing on the host computingdevice 110 (e.g., a controller executing on the host computing device110, comprising the log module 1902, may filter 2402 the one or moredatabase log entries sent to a different location). The commit module1904 executing on the host computing device 110 reroutes 2404 theintercepted 2402 one or more database log entries over the network 115to the volatile memory 1013 of the non-volatile storage device 102(e.g., a controller executing on the host computing device 110,comprising the commit module 1904, may reroute 2404 the one or moredatabase log entries sent to the volatile memory 1013).

The volatile memory 1013 of the non-volatile storage device 102 receives2406 the one or more intercepted 2402 database log entries of thedatabase system 116 a over the network 115 and stores 2408 the one ormore received 2406 database log entries. If the controller 104 (e.g.,the ACM 1011, the commit agent 1020) does not detect 2410 a restartevent or other trigger, the controller 104 acknowledges storage 2408 ofthe one or more database log entries and the storage module 1906receives 2412 the acknowledgment on the host computing device 110 (e.g.,a controller executing on the host computing device 110, comprising thestorage module 1906, may receive 2412 the acknowledgment). The storagemodule 1906 sends 2414 the one or more database log entries from thehost computing device 110 (e.g., from the database system 116 a) to thedifferent non-volatile storage device 121 over the network 115 (e.g., acontroller executing on the host computing device 110, comprising thestorage module 1906, may send 2414 the one or more database log entriesto the second non-volatile storage device 102 in response to thedatabase log entries being received 2406 by the volatile memory buffer1013) and the method 2400 ends. In a further embodiment, the databasesystem 116 a sends 2414 the database log entries to the secondnon-volatile storage device 121 (e.g., a different location), instead ofthe storage module 1906 sending 2414 the one or more database logentries.

If the controller 104 (e.g., the ACM 1011, the commit agent 1020)detects 2410 a restart event or other trigger, the controller 104 (e.g.,the ACM 1011, the commit agent 1020) stores 2416 the one or moredatabase log entries in the non-volatile storage medium 122. Thesecondary power source 124 for the non-volatile storage device 102 mayprovide a power hold-up time to the non-volatile storage device 102after the trigger 2410, during which the volatile memory 1013 may store2408 the one or more database log entries in the non-volatile storagemedium 122. Once the recovery module 1908 determines 2418 that thedetected 2410 restart event is complete (e.g., after the restart eventor other trigger), the recovery module 1908 sends 2420 an identifier forthe database system 116 a to the controller 104 of the non-volatilestorage device 102. The controller 104 determines 2422 that theidentifier for the database system 116 a is received, and the controller104 retrieves 2424 the one or more database log entries from thenon-volatile storage medium 122.

The recovery module 1908 receives 2426 the one or more retrieved 2424database log entries. The storage module 1906 sends 2428 the one or morereceived 2426 database log entries from the host computing device 110(e.g., from the database system 116 a) to the different non-volatilestorage device 121 over the network 115 and the method 2400 ends. Thenon-volatile storage device 102 (e.g., the controller 104) may clear(e.g., delete, remove, invalidate, trim) the one or more database logentries from the non-volatile storage device 102 (e.g., from thevolatile memory 1013 and/or the non-volatile memory medium 122) inresponse to the second non-volatile storage device 121 receiving and/orstoring the one or more database log entries.

A means for storing journal transactions in volatile memory 1013 of astorage device 102, in various embodiments, may include an accelerationmodule 150, a storage management layer 130, a non-volatile storagedevice interface 139, a non-volatile storage medium controller 104, acommit module 1904, an ACM 1011, a commit agent 1020, a storage client116, a database system 116 a, a host computing device 110, a bus 127, anetwork 115, a device driver, a controller (e.g., a device driver, anSML 130, or the like) executing on a host computing device 110, aprocessor 111, other logic hardware, and/or other executable code storedon a computer readable storage medium. Other embodiments may includesimilar or equivalent means for storing journal transactions in volatilememory 1013 of a storage device 102.

A means for storing journal transactions in a second/different storagedevice 121 in response to confirming storage of the journal transactionsin volatile memory 1013, in various embodiments, may include anacceleration module 150, a storage management layer 130, a non-volatilestorage device interface 139, a storage module 1906, a storage client116, a database system 116 a, a host computing device 110, a network115, a device driver, a controller (e.g., a device driver, an SML 130,or the like) executing on a host computing device 110, a processor 111,other logic hardware, and/or other executable code stored on a computerreadable storage medium. Other embodiments may include similar orequivalent means for storing journal transactions in a second/differentstorage device 121.

A means for intercepting journal transactions addressed for asecond/different storage device 121, in various embodiments, may includean acceleration module 150, a storage management layer 130, anon-volatile storage device interface 139, a log module 1902, a storageclient 116, a database system 116 a, a host computing device 110, adevice driver, a filter driver, a controller (e.g., a device driver, anSML 130, or the like) executing on a host computing device 110, aprocessor 111, other logic hardware, and/or other executable code storedon a computer readable storage medium. Other embodiments may includesimilar or equivalent means for intercepting journal transactionsaddressed for a second/different storage device 121.

A means for accessing one or more journal transactions from a firststorage device 102 for storing in a second/different storage device 121in response to a power interruption event, in various embodiments, mayinclude an acceleration module 150, a storage management layer 130, anon-volatile storage device interface 139, a non-volatile storage mediumcontroller 104, a recovery module 1908, an identifier module 1910, anACM 1011, a commit agent 1020, a host computing device 110, a bus 127, anetwork 115, a device driver, a controller (e.g., a device driver, anSML 130, or the like) executing on a host computing device 110, aprocessor 111, other logic hardware, and/or other executable code storedon a computer readable storage medium. Other embodiments may includesimilar or equivalent means for accessing one or more journaltransactions from a first storage device 102 for storing in asecond/different storage device 121 in response to a power interruptionevent.

The present disclosure may be embodied in other specific forms withoutdeparting from its spirit or essential characteristics. The describedembodiments are to be considered in all respects only as illustrativeand not restrictive. The scope of the disclosure is, therefore,indicated by the appended claims rather than by the foregoingdescription. All changes which come within the meaning and range ofequivalency of the claims are to be embraced within their scope.

What is claimed is:
 1. An apparatus comprising: a log module configuredto determine database log records indicating a sequence of operationsperformed on data of a database system; a commit module configured tosend the database log records to one or more volatile memory pagesaccessible over a network, the volatile memory pages configured toensure persistence of the database log records; and a storage moduleconfigured to send the database log records to a non-volatile storagedevice in response to an acknowledgment that the one or more volatilememory pages store the database log records.
 2. The apparatus of claim1, further comprising a recovery module configured to receive one ormore of the database log records persisted by the one or more volatilememory pages in response to recovery from a power interruption event. 3.The apparatus of claim 2, wherein the storage module is configured tosend the received one or more database log records to the non-volatilestorage device in response to receiving the one or more database logrecords after recovery from the power interruption event, the storagemodule failing to send the received one or more database log records tothe non-volatile storage device prior to the power interruption event.4. The apparatus of claim 2, further comprising an identifier moduleconfigured to associate the database log records with a uniqueidentifier, the recovery module configured to receive the one or more ofthe persisted database log records in response to the unique identifierbeing provided.
 5. The apparatus of claim 4, further comprising amigration module configured to migrate the database system to adifferent host computing device by retrieving configuration informationfor the database system using the unique identifier, the configurationinformation comprising at least one or more locations where data for thedatabase system is stored in the non-volatile storage device.
 6. Theapparatus of claim 1, wherein the log module, the commit module, and thestorage module are disposed on a host computing device in communicationwith the one or more volatile memory pages over the network and thestorage module sends the database log records to the non-volatilestorage device from the host computing device.
 7. The apparatus of claim1, wherein the storage module stores the database log records directlyfrom a device comprising the one or more volatile memory pages to thenon-volatile storage device over the network.
 8. An apparatuscomprising: means for storing database log records in volatile memory ofa storage device, the volatile memory configured to ensure persistenceof the database log records in the storage device; and means for storingthe database log records in a second storage device in response to anacknowledgment of storage of the database log records in the volatilememory, the second storage device having a higher latency than thevolatile memory.
 9. The apparatus of claim 8, further comprising meansfor intercepting the database log records addressed for the secondstorage device, wherein the means for storing the database log recordsin the volatile memory stores the database log records in response tointercepting the database log records.
 10. The apparatus of claim 8,further comprising means for accessing one or more of the database logrecords from the storage device for storing in the second storage devicein response to a power interruption event.
 11. The apparatus of claim10, further comprising means for associating the database log recordswith a unique identifier, the means for accessing the one or more of thedatabase log records from the storage device receiving the one or moreof the database log records in response to the unique identifier beingprovided.
 12. The apparatus of claim 11, further comprising means formigrating a database system of the database log records to a differenthost computing device by retrieving configuration information for thedatabase system using the unique identifier, the configurationinformation comprising at least one or more locations where data for thedatabase system is stored in the second storage device.
 13. Theapparatus of claim 8, wherein the means for storing the database logrecords in the second storage device stores the database log recordsdirectly from the storage device to the second storage device.
 14. Amethod comprising: determining database log records indicating asequence of operations performed on data of a database system; sendingthe database log records to one or more volatile memory pages accessibleover a network, the volatile memory pages configured to ensurepersistence of the database log records; and sending the database logrecords to a non-volatile storage device in response to anacknowledgment that the one or more volatile memory pages store thedatabase log records.
 15. The method of claim 14, further comprisingreceiving one or more of the database log records persisted by the oneor more volatile memory pages in response to recovery from a powerinterruption event.
 16. The method of claim 15, wherein sending thedatabase log records to the non-volatile storage device is in responseto receiving the one or more database log records after recovery fromthe power interruption event, having failed to send the one or moredatabase log records to the non-volatile storage device prior to thepower interruption event.
 17. The method of claim 15, further comprisingassociating the database log records with a unique identifier, whereinreceiving the one or more of the persisted database log records is inresponse to the unique identifier being provided.
 18. The method ofclaim 17, further comprising migrating the database system to adifferent host computing device by retrieving configuration informationfor the database system using the unique identifier, the configurationinformation comprising at least one or more locations where data for thedatabase system is stored in the non-volatile storage device.
 19. Themethod of claim 14, wherein the database log records are sent to thenon-volatile storage device from a host computing device over thenetwork.
 20. The method of claim 14, wherein the the database logrecords are stored directly from a device comprising the one or morevolatile memory pages to the non-volatile storage device over thenetwork.